Assertion: Red algae contribute in producing coral reef.
Reason: Some red algae secrete and deposit calcium carbonate on their walls.

Options

A. If both assertion and reason are true and reason is the correct explaination of assertion
B. If both assertion and reason are true but reason is not correct explaination 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 "Red algae contribute in producing coral reef." This implies that red algae play a role in the formation of coral reefs.

2. **Understanding the Reason**: The reason given is that "Some red algae secrete and deposit calcium carbonate on their walls." This indicates a specific mechanism by which red algae contribute to coral reef formation.

3. **Identifying the Type of Red Algae**: The specific type of red algae that contributes to coral reef formation is known as coralline algae. These algae are characterized by their ability to secrete calcium carbonate.

4. **Mechanism of Contribution**: Coralline algae secrete calcium carbonate, which gets deposited on their cell walls. This process leads to the hardening of their structure, which is essential for the formation of coral reefs.

5. **Formation of Coral Reefs**: Coral reefs are formed from the accumulation of various calcareous materials, including the exoskeletons of coral animals, mollusks, and the deposits from coralline algae. The hard exoskeletons provide a protective covering for coral polyps.

6. **Conclusion**: Since coralline algae are a type of red algae and they contribute to the formation of coral reefs through the secretion of calcium carbonate, both the assertion and the reason are true. Furthermore, the reason provides a correct explanation for the assertion.

7. **Final Answer**: Therefore, the correct answer is (A) Both assertion and reason are true, and the reason is the correct explanation of the assertion.

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