Assertion : Cytokinins lead to retention of chlorophyll and delay the senescence in leaves.
Reason: cytokinins are only responsible for root primordia formation.

Options

A. If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.
B. If both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.
C. If Assertion is true but the Reason is false.
D. If both Assertion and Reason are false.

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Cytokinins lead to retention of chlorophyll and delay the senescence in leaves."
- Cytokinins are indeed a type of plant hormone that plays a significant role in promoting cell division and delaying aging (senescence) in plant tissues, particularly in leaves. They help in the retention of chlorophyll, which is essential for photosynthesis.

2. **Understanding the Reason**:
- The reason states that "Cytokinins are only responsible for root primordia formation."
- This statement is incorrect. While cytokinins do have a role in root development, they are not solely responsible for root primordia formation. Auxins are primarily responsible for this process. Therefore, this reason does not accurately describe the role of cytokinins.

3. **Evaluating the Relationship**:
- Since the assertion is true and the reason is false, we need to determine the correct option based on this evaluation.

4. **Conclusion**:
- The appropriate answer is that the assertion is true, but the reason is false. Therefore, the correct option is the third one.

### Final Answer:
The assertion is true, but the reason is false.

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