A: Forminiferans have a calcareous shell.
R: Dimorphic nucleic are present in Paramecium.

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

**Step-by-Step Solution:**

1. **Identify the Assertion and Reason:**
- Assertion (A): Foraminiferans have a calcareous shell.
- Reason (R): Dimorphic nuclei are present in Paramecium.

2. **Evaluate the Assertion:**
- Foraminiferans are a type of protozoan protists that belong to the group Sarcodina. They are known for having a calcareous shell, which is made up of calcium carbonate. This statement is true.

3. **Evaluate the Reason:**
- Paramecium is another type of protozoan, specifically classified as a ciliated protozoan. Paramecium possesses two types of nuclei: a macronucleus and a micronucleus. This statement is also true.

4. **Determine the Relationship Between Assertion and Reason:**
- Although both statements are true, the reason provided (dimorphic nuclei in Paramecium) does not explain or relate to the assertion (calcareous shell in foraminiferans). Therefore, the reason does not support the assertion.

5. **Conclusion:**
- Since both the assertion and the reason are true but the reason does not correctly explain the assertion, the correct answer is that the assertion is true, and the reason is true but not the correct explanation for the assertion.

**Final Answer:**
- The assertion is true, and the reason is true but does not explain the assertion.

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