The infectious agents made up of RNA only are

Options

A. Viroids
B. Bacteria
C. Fungi
D. Virus

Answer

To answer the question regarding the infectious agents made up of RNA only, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are pyroids, bacteria, fungi, and viruses. We need to determine which of these is made up solely of RNA.

2. **Understanding Viroids**: Viroids are known to be infectious agents that consist of a single-stranded RNA molecule. They do not have a protein coat, which distinguishes them from viruses.

3. **Analyzing Bacteria**: Bacteria are prokaryotic organisms that contain DNA as their genetic material, not RNA. Therefore, they cannot be the answer.

4. **Analyzing Fungi**: Fungi also have DNA as their genetic material, so they do not fit the criteria of being made up of RNA only.

5. **Analyzing Viruses**: Viruses can have either DNA or RNA as their genetic material. They typically have a protein coat (capsid) surrounding them, which viroids lack. Therefore, while some viruses may contain RNA, they are not exclusively made up of RNA.

6. **Conclusion**: Based on the analysis, the only infectious agent made up of RNA only is **viroids**.

### Final Answer:
The infectious agents made up of RNA only are **viroids**.

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