$ The first formed embryonic cavity is called blastocoel.
! Annelids have a segmented body.

Options

A. If both As and R are correct and R is correct explanation of As
B. If both As and R are correct but R is not correct explanation of As
C. If As is correct, R is wrong
D. If both As and R are wrong.

Answer

To solve the question regarding the statements about the blastocoel and annelids, we will break it down into two parts.

### Step-by-Step Solution:

1. **Understanding the First Statement:**
- The first statement claims that "the first formed embryonic cavity is called blastocoel."
- After fertilization, the zygote undergoes cleavage, leading to the formation of a hollow ball of cells known as the blastula.
- Within this blastula, the first cavity that forms is indeed called the blastocoel. This cavity is filled with fluid and is crucial for the development of the embryo.

2. **Conclusion for the First Statement:**
- Since the blastocoel is the first embryonic cavity formed during the development of the embryo, the first statement is **true**.

3. **Understanding the Second Statement:**
- The second statement claims that "Annelids have a segmented body."
- Annelids, which belong to the phylum Annelida, are characterized by their segmented bodies. Examples include earthworms and leeches.
- The segmentation in annelids allows for more efficient movement and flexibility, as each segment can function somewhat independently.

4. **Conclusion for the Second Statement:**
- Since annelids do indeed have a segmented body structure, the second statement is also **true**.

5. **Final Evaluation:**
- Both statements are true, but the question may require us to evaluate if one statement explains the other. In this case, while both are true, the second statement does not provide a direct explanation for the first.

### Final Answer:
Both statements are true, but the second statement does not explain the first. Therefore, the correct response is **Option B**: Both A and R are correct, but R is not the correct explanation for A.

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