At a certain point, probably during the great bombardment (of meteorites) some 4.4 Gy ago the Earth had no atmosphere at all - it was too hot and gravity wasn ’t strong enough. We know this because our current atmosphere contains very little 36Ar (implying that 99% of the current argon is due to K40 decay). In the Sun, 36Ar is much more common (by a factor of say 10,000). The Earth cooled and icy comets continued to bring water, ammonia, carbon oxides, hydrogen cyanide, formaldehyde and other simple compounds. We can still detect these chemical in space. There was no oxygen gas.

Stanley Miller conducted a famous experiment in 1953 to provide experimental proof that hydrogen, methane, water, and ammonia can give rise to amino acids, the building blocks of proteins. The experiment was based on the hypothesis proposed by Russian scientist Alexander Oparin. Miller identified several amino acids, including glycine, alanine, and aspartic acid, in the mixture. The experiment demonstrated that simple organic molecules, such as amino acids, can be formed under conditions similar to those believed to exist on early Earth.

• Louis Pasteur in his swan neck flask experiment, found out that life originated from pre-existing life.
• He prepared sterilized syrup of sugar and later killed yeast by boiling them in flasks.

The primitive atmosphere of earth was reducing atmosphere with little or no oxygen but was rich in water vapour, carbon monoxide, carbon dioxide, nitrogen and hydrogen. Thus, oxygen was not present in primitive atmosphere. The high temperature, UV light and lightening provided energy for chemical reactions between hydrogen and free oxygen, nitrogen and carbon to form, ammonia, methane and cyanides. Owing to the high temperature of earth, water was present in form of superheated steam and ammonia, methane and cyanides were present in gaseous form. 

Therefore, the correct answer is option C.

• This theory states that life originates from nonliving things or decaying matter like mud, straw etc. spontaneously.
• It was theory which had no specific explanation. It was soon rejected.

• It was at 800 °C in which the flask was maintained along with electric discharge.
• A moderately high temperature was required to keep the flask sterilized.
• Thus, creating amino acids as the product.

Miller took a mixture of water, methane, ammonia and hydrogen in a closed flask at 800 °C.

• It was done in a closed flask and using electric discharge tubes, and later observed the formation of amino acids.

Origin of earth dates back around 4.6 billion years ago which makes options A and B incorrect as life originated only after the origin of earth. The period of 4.6 billion year ago to 3.8 billion years ago is termed as the Azoic era when the primitive earth conditions were too harsh to sustain any life form. During this period, the earth 's temperature cooled down and the ocean and atmosphere were formed. The Archaeozoic era is marked by the appearance of first life form in the hot soup of the primitive ocean which dates back around 4 billion years ago. The first life forms were prokaryotic chemoheterotrophic anaerobic organisms.

Answer:
In his experiment, Stanley Miller synthesized the following:
- Virus: Not synthesized by Stanley Miller in his experiment.
- Protein: Not synthesized by Stanley Miller in his experiment.
- Amino acid: Stanley Miller successfully synthesized amino acids in his experiment. Amino acids are the building blocks of proteins and are essential for life.
- Cell: Stanley Miller did not synthesize cells in his experiment.
Therefore, the correct answer is option C: Amino acid. Stanley Miller 's experiment demonstrated that the conditions present in the early Earth 's atmosphere can lead to the formation of amino acids, which is an important step in the origin of life on Earth.

DNA is a polymer of nucleotide.Nucleotides are the elementary unit that forms DNA. It is made up of three components- nitrogenous base, a pentose sugar, and phosphate. It is formed through phosphorylation of nucleoside. Chain of nucleotides or the polymer of nucleotide is the DNA. It is acidic in nature.