[A]: Daily periodicity of stomata! movement is not the characteristic of succulent plants.
[R]: In succulent plants stomata are closed at night and open during the day.

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 regarding the daily periodicity of stomatal movement in succulent plants, we can break down the solution into clear steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Daily periodicity of stomatal movement is not a characteristic of succulent plants."
- We need to evaluate whether this statement is true or false.

2. **Evaluating the Assertion**:
- Succulent plants, such as cacti, have adapted to arid environments and exhibit a unique stomatal behavior.
- They typically open their stomata at night and close them during the day to minimize water loss through transpiration.
- Therefore, the assertion is **false** because daily periodicity (the regular opening and closing of stomata) is indeed a characteristic of succulent plants.

3. **Understanding the Reason**:
- The reason states that "In succulent plants, stomata are closed at night and open during the day."
- We need to determine if this statement is true or false.

4. **Evaluating the Reason**:
- As mentioned earlier, succulent plants open their stomata at night (to take in CO2) and close them during the day (to conserve water).
- Thus, the reason is also **false**.

5. **Conclusion**:
- Both the assertion and the reason are false.
- Therefore, the correct answer is option D, which states that both the assertion and reason are false.

### Final Answer:
Both the assertion and reason are false (Option D).

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