[A]: Stomata remain open during day
[R]: Stomata help in gaseous exchange.

Options

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

Answer

To solve the assertion and reason question regarding stomata, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Assertion**: The assertion states that "Stomata remain open during the day." We need to determine if this statement is true or false.

- **Explanation**: Stomata are small openings found mostly on the leaves of plants. They open during the day to facilitate gas exchange and are primarily influenced by light and turgor pressure in guard cells.

2. **Evaluate the Reason**: The reason states that "Stomata help in gaseous exchange." We need to assess the truthfulness of this statement as well.

- **Explanation**: Stomata indeed play a crucial role in the process of gaseous exchange, allowing carbon dioxide to enter for photosynthesis and oxygen to exit as a byproduct.

3. **Determine the Truth of Both Statements**:
- Both the assertion and the reason are true based on our understanding of stomata and their functions.

4. **Assess the Relationship Between Assertion and Reason**: We need to determine if the reason correctly explains the assertion.

- **Explanation**: While both statements are true, the reason does not specifically explain why stomata are open during the day. The opening of stomata is primarily due to light and turgor pressure in guard cells, not solely because they facilitate gaseous exchange.

5. **Choose the Correct Option**: Based on the evaluations:
- Both the assertion and reason are true, but the reason does not provide a correct explanation for the assertion.

### Final Answer:
The correct option is **B**: Both assertion and reason are true, but the reason is not the correct explanation for the assertion.

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