Assertion . Pili are tubular structures present in bacteria which help in conjugation
Reason. Formation of pili is controlled by `F^(+)` or fertility factor.

Options

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

Answer

To solve the Assertion-Reason question, we will analyze both the assertion and the reason step by step.

### Step 1: Analyze the Assertion
- **Assertion**: "Pili are tubular structures present in bacteria which help in conjugation."
- **Explanation**: Pili are indeed hair-like appendages found on the surface of many bacteria. They play a crucial role in the process of conjugation, which is a form of genetic exchange between bacterial cells. During conjugation, a donor bacterium transfers genetic material to a recipient bacterium through the pili.

### Step 2: Analyze the Reason
- **Reason**: "Formation of pili is controlled by F^(+) or fertility factor."
- **Explanation**: The formation of pili, specifically sex pili, is indeed controlled by the fertility factor, often denoted as F^(+). This factor is a plasmid that carries genes responsible for the synthesis of pili, which are essential for the conjugation process. Bacteria that possess the F^(+) factor can form sex pili and transfer genetic material to other bacteria.

### Step 3: Determine the Relationship
- Both the assertion and the reason are true statements.
- The reason provides a correct explanation for the assertion because the ability of bacteria to form pili (and thus engage in conjugation) is indeed dependent on the presence of the fertility factor.

### Conclusion
- Therefore, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

### Final Answer
Both assertion and reason are true, and the reason is the correct explanation of the assertion.

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