Assertion : In collateral vascular bundles phloem is situated toward inner side.
Reason : In monocot stem, cambium is present .

Options

A. (a) If both A and R are true and R is the correct explanation of A
B. (b) If both A and R are true but R is not the correct explanation of A
C. (c) If A is true and R is false
D. (d) If both A and R are false

Answer

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

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that in collateral vascular bundles, phloem is situated toward the inner side.
- In reality, in collateral vascular bundles, the phloem is located on the outer side and the xylem is on the inner side. Therefore, this assertion is **false**.

2. **Understanding the Reason**:
- The reason states that in monocot stems, cambium is present.
- In monocots, the vascular bundles are typically closed collateral bundles, which means they lack cambium. Hence, this reason is also **false**.

3. **Conclusion**:
- Since both the assertion and the reason are false, the correct answer to the question is option D: Both assertion and reason are false.

### Final Answer:
**D: Both assertion and reason are false.**

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