Assertion : Repeated muscle expansions and contractions make the earthworm move through the soil.
Reason : Earthworms help to make the soil fertile, loose and porous.

Options

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

Explanation

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that "repeated muscle expansions and contractions make the earthworm move through the soil." This is accurate because earthworms do not have bones; they rely on their muscles to contract and expand, allowing them to push through the soil.

2. **Understanding the Reason**: The reason given is that "earthworms help to make the soil fertile, loose, and porous." This is also true. Earthworms contribute to soil fertility by breaking down organic matter and leaving behind nutrient-rich waste, which improves soil structure.

3. **Analyzing the Relationship**: While both the assertion and the reason are true, the reason does not explain why the earthworm moves. The movement of the earthworm is due to muscle contractions, while the fertility of the soil is a separate benefit provided by the earthworm.

4. **Conclusion**: Since both the assertion and the reason are true, but the reason does not serve as a correct explanation for the assertion, the correct option is: "Both assertion and reason are true, but reason is not the correct explanation."