**Core Concept**
The question is testing the understanding of the fundamental process of DNA replication, specifically the enzyme responsible for RNA-directed DNA synthesis. This process is crucial for the replication of genetic material during cell division.

**Why the Correct Answer is Right**
The correct answer is an enzyme called Reverse Transcriptase (RT). Reverse Transcriptase is a type of RNA-dependent DNA polymerase, which uses RNA as a template to synthesize a complementary DNA (cDNA) strand. This enzyme is essential for the replication of retroviruses, such as HIV, and is also used in molecular biology techniques like RT-PCR. Reverse Transcriptase works by reading the RNA template and adding nucleotides to a growing DNA chain, effectively making DNA from RNA.

**Why Each Wrong Option is Incorrect**
**Option A:** DNA Polymerase - While DNA Polymerase is crucial for DNA replication, it uses a DNA template to synthesize a new DNA strand, not RNA.

**Option B:** RNA Polymerase - RNA Polymerase is responsible for transcription, the process of making RNA from a DNA template, not the reverse process.

**Option C:** Helicase - Helicase is an enzyme that unwinds DNA double helices, allowing other enzymes to access the template strands, but it is not involved in RNA-directed DNA synthesis.

**Clinical Pearl / High-Yield Fact**
Remember that Reverse Transcriptase is a key enzyme in the life cycle of retroviruses, and its inhibition is a crucial step in antiretroviral therapy for HIV.

**Correct Answer: C. Reverse Transcriptase.**