The correct answer is option C) Reverse transcriptase.

Reverse transcriptase is an enzyme that catalyzes the synthesis of DNA from an RNA template. This process is called reverse transcription. It is a crucial step in the replication of retroviruses, such as HIV.

Explanation:
1. Reverse transcription:
Reverse transcription is the process of synthesizing DNA using an RNA template. It is a unique process because the typical flow of genetic information is from DNA to RNA (transcription) and then from RNA to protein (translation). However, in certain cases, such as retroviruses, the flow is reversed.

2. Retroviruses:
Retroviruses are a group of viruses that have RNA as their genetic material. When a retrovirus infects a host cell, it carries with it the enzyme reverse transcriptase. This enzyme allows the retrovirus to convert its RNA genome into DNA, which can then be integrated into the host cell's genome.

3. Reverse transcriptase:
Reverse transcriptase is an enzyme that catalyzes the synthesis of DNA from an RNA template. It is unique because most DNA polymerases can only synthesize DNA using a DNA template. Reverse transcriptase is found in retroviruses and some other RNA viruses, as well as in certain cellular organisms, such as bacteria and yeast.

4. Steps of reverse transcription:
The process of reverse transcription involves several steps:
a) Binding: Reverse transcriptase binds to the RNA template.
b) Synthesis of DNA: The enzyme synthesizes a complementary DNA strand using the RNA template as a guide. This process is similar to DNA replication, where nucleotides are added one by one to the growing DNA strand.
c) RNA degradation: The RNA template is degraded, leaving behind a DNA-RNA hybrid.
d) Second DNA strand synthesis: Reverse transcriptase synthesizes a second DNA strand using the DNA-RNA hybrid as a template. This results in the formation of a double-stranded DNA molecule.
e) Integration: The double-stranded DNA molecule can then be integrated into the host cell's genome, allowing the retrovirus to replicate and produce more viral particles.

In conclusion, reverse transcriptase is the enzyme that uses RNA as a template to synthesize DNA. This process, known as reverse transcription, is essential for the replication of retroviruses and plays a crucial role in their life cycle.

DNA is synthesised from RNA Template with the help of enzyme reverse transcriptase and the process is called reverse transcription.