Assertion: Prions are proteinaceous infectious particles.
Reason: Prions possess no nucleic acid.

Options

A. If both A and R are true, and R is the correct explanation of A
B. If both A and R are true, but R is not the correct explanation of A
C. If A is true but R is false
D. If both A and R are false

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that "Prions are proteinaceous infectious particles." This means that prions are infectious agents that are primarily made up of proteins.

2. **Understanding the Reason**: The reason given is "Prions possess no nucleic acid." This indicates that prions do not contain DNA or RNA, which are the typical genetic materials found in most infectious agents like viruses and bacteria.

3. **Analyzing the Assertion**: The statement about prions being proteinaceous infectious particles is true. Prions are indeed proteins that can cause diseases by inducing abnormal folding of normal cellular proteins.

4. **Analyzing the Reason**: The reason that prions possess no nucleic acid is also true. Unlike viruses that have nucleic acids, prions do not have any genetic material, which is a unique characteristic that differentiates them from other infectious agents.

5. **Conclusion**: Since both the assertion and the reason are true, and the reason correctly explains the assertion, we conclude that the relationship between the two statements is valid.

**Final Answer**: Both the assertion and reason are true, and the reason correctly explains the assertion.

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