[A] : 2,4-D is a herbicide
[R] : It is not used during showing of crops

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

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "2,4-D is a herbicide."
- We need to confirm whether this statement is true or false.

2. **Definition of 2,4-D**:
- 2,4-D stands for 2,4-Dichlorophenoxyacetic acid, which is indeed a chemical compound used as a herbicide.
- Herbicides are substances that are used to kill unwanted plants or weeds.

3. **Conclusion on Assertion**:
- Since 2,4-D is used to kill unwanted plants, we conclude that the assertion is **true**.

4. **Understanding the Reason**:
- The reason states that "It is not used during sowing of crops."
- We need to analyze why herbicides like 2,4-D are not used during the sowing of crops.

5. **Impact of Herbicides on Crops**:
- If herbicides are applied during the sowing of crops, they can harm the main crop plants along with the weeds.
- Therefore, herbicides are typically applied after the crops have grown to a certain extent, allowing them to target the weeds without damaging the crops.

6. **Conclusion on Reason**:
- The reason is also **true** because it correctly explains the timing of herbicide application to avoid harming the main crops.

7. **Relationship Between Assertion and Reason**:
- While both the assertion and the reason are true, the reason does not directly explain why 2,4-D is classified as a herbicide.
- The assertion is about the classification of 2,4-D, while the reason discusses its application timing.

8. **Final Answer**:
- The correct option is that both the assertion and reason are true, but the reason is not the correct explanation of the assertion.