The underlined part of the sentence is grammatically incorrect.

• The underlined part needs correction in adjective and noun.
  
  
• The verb “expressed” needs an object. A noun/pronoun can be its object. But here, we have used “grieve” (a verb) as its object. This is wrong. The correct Noun form “grief” must be used and it means “very sad especially when someone dies”.
  
  
• Also, “depth” is a noun. But we need an adjective form to qualify the noun “grief”. Thus, “deep” should be used. In the context of emotions, it means “strongly felt”.
  
  
• Hence, “deep grief over the” is the correct improvement.

Thus, the correct sentence will be:  The Prime Minister has expressed deep grief over the demise of renowned bollywood actor.

Hence, option C is the correct answer.

The underlined part of the sentence is grammatically incorrect.

• The underlined part needs correction in noun and helping verb.
  
  
• “Doze” as a noun means a short period of sleep esp. during the day. Whereas the given sentence demands a noun connected with “vaccine” or we can say related to “medicine/drug”. Thus, the correct noun “dose” should be used. It means “an amount of medicine or drug that is taken once or regularly over a period of time.” Also, the word “90 crore” makes it mandatory to use the plural form of “dose” i.e. “doses”.
  
  
• Also, “doses” being a plural noun will take the plural helping verb with it in accordance with the subject verb agreement. Thus, “have” should be used.
  
  
• Hence, “doses have been” is the correct improvement.

Thus, the correct sentence will be:  90 crore vaccine doses have been administered so far under Nationwide Vaccination Drive.

Hence, option A is the correct answer.

The underlined part of the sentence is grammatically incorrect.

* The underlined part needs correction in verb and adjective.

* Before the underlined part, the word “to” shows that we have to use the base form of verb to complete the Infinitive form of verb. Thus, “discard” should be used.   Note: Discarded is the third form the verb.

* Also, an Infinitive being a Semi Verb takes an object after it. Here, “vehicles” (a noun) is the object of the infinitive. “Older” is a comparative degree of adjective but its usage is wrong here because there is no context of comparison. Thus, we have to use the positive degree of adjective i.e. “old” to qualify the noun “vehicles”.

* Hence, “discard old vehicles” is the correct improvement.

Thus, the correct sentence will be: It is proposed to have a system of incentives and disincentives to nudge vehicle owners to discard old vehicles.
Hence, option B is the correct answer.

The underlined part of the sentence is grammatically incorrect.

* The underlined part needs correction in determiner and verb.

* As a determiner, “This” is used for singular nouns and “These” is used for plural nouns. Here, “plants” is a plural noun hence “these” should be used here.

For example:

There was a court case resulting from this incident.

These glasses allow you to see the film in 3D.

* Also, modal verb takes the base form of verb after it. Here, “served” is the third form of verb after “will” (a modal verb). Thus, base form of the verb “serve” should be used.

* Hence, “these oxygen plants will serve” is the correct improvement.

Thus, the correct sentence will be: The district magistrate said that these oxygen plants will serve as a major boost to oxygen availability at the district level.

Hence, option C is the correct answer.

The underlined part of the sentence is grammatically incorrect.

* The underlined part needs correction in article and verb.

* “Occasion” is a noun with a vowel sound. Thus, using indefinite article “a” before is incorrect. We have to use “an” for the nouns with vowel sound.

For example:

We spent an hour in the garden.

* Also, infinitive form of verb takes the base form of verb after “to”. But here, a noun “rededication” is used after it. This is wrong. Thus, first form of the verb i.e. “rededicate” should be used after “to”.

* Hence, “an occasion to rededicate” is the correct improvement.

Thus, the correct sentence will be: The Governor said that Panchayati Raj Day is an occasion to rededicate ourselves to the pledge of redevelopment of rural India.

Hence, option A is the correct answer.

The underlined part of the sentence is grammatically incorrect.

* The underlined part needs correction in adverb and preposition.

* “Acceptable” is an adjective and it means that someone agrees is of a good standard or allowed. Here, we need an adverb to qualify this adjective. But we have used “ease” (act like noun or verb) which cannot qualify it. Thus, appropriate adverb form i.e. “easily” should be used. It means “without problems or difficulty”

* Also, preposition “of” is used for selection out of many things available OR for showing possession. Here, both the contexts are missing. We have to use a pronoun that reflects the sense of “purpose” because we have to connect the “acceptable” with “loan formalities”. Thus, preposition “of” can be used to show the purpose.

For example:

A gentle form of exercise will increase your ability to relax.

We got a new table for the dining room.

* Hence, “easily acceptable for loan” is the correct improvement.

Thus, the correct sentence will be: The finance secretary urged banks to ensure easy credit by preparing a format of property card that is easily acceptable for loan formalities.

Hence, option B is the correct answer.

The underlined part of the sentence is grammatically incorrect.

* The underlined part needs correction in preposition and noun.

* Usually we use preposition “into” with verb “transformation” to show the change in state. Here, the state of building has been changed into some useful purpose i.e. for a shelter. Thus, “into” should be used here.

* “Onto” as a preposition shows the movement on to a particular place or situation. Thus, it is wrong to use it here.

* Also, object of preposition should be a noun or a pronoun. But here, we have used verb form “sheltered” which is wrong. Thus, appropriate noun form i.e. “shelter” should be used. It means “the fact of having a place to live or stay”.                     
Note: “Shelter” can be Noun or Verb depending on its usage in the sentence.

* Hence, “into a shelter” is the correct improvement.
Thus, the correct sentence will be:  An unoccupied building has been transformed into a shelter for street dogs on the outskirts of the city.

Hence, option A is the correct answer.

• The underlined segment is erroneous.

• 'Should have done' is used for saying what was the right thing to do when you realize that someone did not do it.

• For example, you should have taken my advice.

• The sentence uses the expression “it is time”.

• We use simple past tense with it to refer to the present moment.

e.g. Gosh! It’s almost midnight. It’s time we went home.

• Thus, replace “should have done” with “did” to make the sentence grammatically sound.

The correct sentence will be: It is time we did something useful.

• The underlined segment is erroneous.

• When a story is told in the past tense, the adverbial ‘no sooner’ is often used to emphasise that one event quickly followed another.

• ‘No sooner’ is always followed by ‘than’ and not ‘when’ or ‘before’.

• For example, No sooner had the company launched its new product than it went bankrupt.

• However, in the given sentence, 'when' is used.

• 'Scarcely' is always followed by ‘when’ or ‘before’ and not ‘than’.

• If ‘scarcely’ is in the initial position, the subject and auxiliary are inverted.

• For example, scarcely had she finished reading when she fell asleep.

• Hence, the underlined segment should be replaced with 'scarcely had she' to make the sentence grammatically correct.

• Therefore, option D is the correct answer, and the correct sentence is – Scarcely had she put the baby to sleep when a loud noise woke him up.

The underlined part is grammatically incorrect.

• The underlined part needs a verb that justifies proper reasoning “why Rahul is tired”. This is possible only when someone is doing something in the perfect continuous tense. Also, the sentence given here is in present tense; hence present perfect continuous tense should be used. “has been working” is the correct form of the verb here.

• The present perfect continuous shows that something started in the past and is continuing at the present time. The present perfect continuous is formed using the construction has/have been + the present participle (root + -ing).

• Also, “8 o’clock” is a specific point of time. So it is better to use “since” with it.

• Hence, “has been working since” is the correct improvement.

Thus, the correct sentence will be: Rahul, an employee of a top management firm, is tired as he has been working since 8 o’clock in the evening.

Hence, option B is the correct answer.