Assertion (A): Fossils are remains of dead organisms.
Reason (R): It is helpful in study of evolution .

Options

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is NOT the correct explanation of A.
C. A is true but R is false.
D. A is false and R is true.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that "Fossils are remains of dead organisms."
- This is a factual statement. Fossils are indeed the preserved remains, impressions, or traces of organisms that lived in the past and are no longer alive.

2. **Understanding the Reason (R)**:
- The reason given is that "It is helpful in the study of evolution."
- This statement is also true. Fossils provide crucial evidence for understanding the history of life on Earth, including how different species have evolved over time.

3. **Analyzing the Relationship**:
- While both the assertion and the reason are true, we need to determine if the reason is a correct explanation of the assertion.
- The assertion talks about what fossils are, while the reason discusses their importance in studying evolution. They are related concepts, but the reason does not directly explain why fossils are defined as remains of dead organisms.

4. **Conclusion**:
- Therefore, both the assertion and the reason are true, but the reason does not serve as a correct explanation for the assertion.

### Final Answer:
- Assertion (A) is true.
- Reason (R) is true.
- However, the reason (R) is not a correct explanation of the assertion (A).