Viruses are haploid having only one genome. But Which group of viruses is diploid and have two genomes?

Options

A. (a) retroviruses
B. (b) reoviruses
C. (c) riboviruses
D. (d) zoophages.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about a specific group of viruses that are diploid, meaning they have two genomes, in contrast to most viruses that are haploid with only one genome.

2. **Identifying Virus Groups**: To answer the question, we need to explore different groups of viruses and their genomic structures. The primary groups to consider include retroviruses, rheoviruses, riboviruses, and zoophages.

3. **Analyzing Retroviruses**: Retroviruses are known for their unique ability to reverse transcribe their RNA into DNA. They possess two sets of genomes, specifically two identical strands of RNA. This characteristic makes them diploid.

4. **Examining Other Virus Groups**:
- **Rheoviruses**: These viruses have one set of double-stranded RNA, making them haploid.
- **Riboviruses**: These contain one set of single-stranded RNA, also haploid.
- **Zoophages**: These are viruses that infect animals and typically have one set of double-stranded DNA, making them haploid as well.

5. **Conclusion**: After analyzing the different groups, it is clear that retroviruses are the only group that is diploid, having two genomes.

6. **Final Answer**: The group of viruses that is diploid and has two genomes is **retroviruses**.

---