Nucleic acid does not occur in

Options

A. Prion
B. Viroid
C. Virus
D. Mycoplasma.

Answer

### Step-by-Step Solution:

1. **Understanding Nucleic Acids**: Nucleic acids are essential macromolecules found in all living cells and viruses. They include DNA and RNA, which are crucial for genetic information and function.

2. **Identifying the Options**: The question provides four options:
- Prion
- Viroid
- Virus
- Mycoplasma

3. **Analyzing Each Option**:
- **Prion**: Prions are misfolded proteins that do not contain nucleic acids. They are known to cause neurodegenerative diseases in humans and animals (e.g., Creutzfeldt-Jakob disease, mad cow disease).
- **Viroid**: Viroids are composed of single-stranded RNA and do not have a protein coat. They do contain nucleic acids (RNA).
- **Virus**: Viruses consist of nucleic acids (either DNA or RNA) surrounded by a protein coat. Therefore, they do contain nucleic acids.
- **Mycoplasma**: Mycoplasma are a type of bacteria that contain DNA. Thus, they also contain nucleic acids.

4. **Conclusion**: Among the options, prions are the only entities that do not contain nucleic acids. Therefore, the correct answer to the question "Nucleic acid does not occur in" is **Prion**.

### Final Answer:
Nucleic acid does not occur in **Prion**.

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