Assertion :- Old woody plant parts are devoid of primary phloem.
Reason :- Primary phloem gets crushed due to continuous formation and accumulation of secondary xylem.

Options

A. If both Assertion & Reason are True & Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but the Reason is a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are false.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that old woody plant parts are devoid of primary phloem. This means that in older parts of woody plants, the primary phloem is no longer present.

2. **Understanding the Reason**: The reason provided states that primary phloem gets crushed due to the continuous formation and accumulation of secondary xylem. This implies that as the plant grows and forms more secondary xylem, the space for the primary phloem decreases, leading to its crushing.

3. **Role of Cambium**: Cambium is a layer of meristematic tissue located between the xylem and phloem. It is responsible for secondary growth in plants. As cambium becomes more active, it produces more secondary xylem (wood) and secondary phloem.

4. **Process of Secondary Growth**: During secondary growth, the cambium divides and differentiates to produce secondary xylem towards the inside and secondary phloem towards the outside. As secondary xylem accumulates, it increases in volume.

5. **Effect on Primary Phloem**: The accumulation of secondary xylem pushes against the primary phloem, which does not have the ability to expand as much. As a result, the primary phloem gets crushed due to the pressure from the expanding secondary xylem.

6. **Conclusion**: Both the assertion and the reason are correct. The reason correctly explains why the assertion is true. Therefore, the answer is that both the assertion and reason are correct, and the reason is a correct explanation for the assertion.

### Final Answer:
Both the assertion and reason are correct, and the reason is a correct explanation for the assertion.

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