The correct answer is option 1 i.e. at once.

At once means immediately or right away.

The sentence implies that the person agreed to the idea of going to the mall without any delay.

Hence, to express the narrator's immediate agreement 'at once' is the perfect fit for the blank.

Other options:

At large means as a whole.

At most means not more than a maximum point/quantity

At ease means to be confident or relaxed about something.

The correct answer is option 1, i.e. for.

We use 'for' when we measure the duration or when we say how long something lasts.

The rest of the given options imply different meanings, whereas as per the context the sentence talks about a particular period of time during when schools were closed due to excessive heat.

Hence, 'for' becomes the correct fill for the blank.

The correct answer is option 4 i.e. a worse.

We need to use the "worst" movie because it is being compared with all movies that have been seen. The correct form of the adjective should be the superlative (not comparative).

When using superlative adjectives such as best, worst, etc., we always use the before the adjective.

The correct sentence will be - I am telling you it was the worst movie I’ve ever seen in my life.

The correct answer is option 3 i.e. yet raining.

We use yet as an adverb to refer to a time which starts in the past and continues up to the present.

We use it mostly in negative statements or questions in the present perfect. It usually comes in the end position.

Example: Kamal hasn’t registered for class yet.

Correct sentence: Please go out and check if it is raining yet.

The correct answer is option 3 i.e. at the kitchen.

We need to replace "at the kitchen" with "in the kitchen" to make the sentence grammatically correct.

In (preposition)- expressing the situation of something that is or appears to be enclosed or surrounded by something else.

As the kitchen is an enclosed place "in" will the suitable use.

The correct sentence will be- Instead of helping her mother in the kitchen, Rekha was on her mobile talking to her friend.

The correct answer is option 4 i.e. and resulting in mass fatalities.

The error lies in part 4 of the sentence.

We need to change "resulting" into "resulted" to make the sentence grammatically correct.

The part of speech joined with AND should always be the same- witnessed shooting and resulted.

The correct sentence will be- Two American cities, witnessed shooting and resulted in mass fatalities over the weekend.

The correct answer is option 2 i.e. it is be said.

We need to change "Be" into 'being' to make sentences grammatically correct.

The correct structure is - subject + is/am/are + v4.

The correct sentence will be- It is being said that in 2019 the Indian Stock Market will fall drastically and we can expect that fall very soon.

The correct answer is option 1 i.e. along public exhibition.

• We need to use "along with" in place of "along" to make the sentence grammatically correct.
• Along with - in company with or at the same time as.
• As the statement shows the sense of additional, the use of "along with" is necessary.

The correct sentence will be: Each film will be checked by a government-appointed censor board along with public exhibition.

The correct answer is option 2 i.e. find the distinction marks.

1. The error lies in option 2 because of the wrong use of "Tense".
2. We need to replace "Find" with "Found" to make the statement grammatically correct.

Grammatical concept:- 

• There is an adverb "Yesterday" in the given statement that is used to show the past time.
• Because of the "Past Time," we need to use "Past tense" in the given statement.
• The chosen option contains the ERROR hence, it will be the correct choice.

Correct Sentence:-

While checking your exam result yesterday I found the distinction marks in all the subjects.

The correct answer is option 1 i.e. Chenab Bridge, a world's highest railway.

1. The error lies in part 1 of the statement because of the wrong use of "Article".
2. We need to replace "A" with "THE" to make the statement grammatically correct.

Grammatical concept:- 

• As there is a use of the superlative degree form of the adjective in the given statement we need to use the article "the" before it.
• A superlative degree is always followed by the article "the".
• Hence, the chosen option will be correct.

The correct sentence will be- 

Chenab Bridge, the world's highest railway bridge, is all set to complete an important construction milestone by March 2021.