Assertion :- Different aged rock sediments contain fossils of different life forms.
Reason :- Certain life forms are restricted to certain geological time-spans.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are False.

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Different aged rock sediments contain fossils of different life forms."
- This is true because the geological time scale shows that various life forms existed at different times in Earth's history. Fossils found in sedimentary rocks can indicate the age of the rocks based on the types of organisms that were present during that time.

2. **Understanding the Reason**:
- The reason given is "Certain life forms are restricted to certain geological time-spans."
- This statement is also true. Different species have evolved and become extinct over geological time, meaning that certain fossils are only found in specific layers of rock that correspond to the time period when those species existed.

3. **Connecting Assertion and Reason**:
- The reason explains why the assertion is true. Since certain life forms are restricted to certain geological time spans, it logically follows that different aged sediments will contain fossils of different life forms.

4. **Conclusion**:
- Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both statements are true, and the reason is the correct explanation of the assertion.

### Final Answer:
Both the assertion and the reason are true, and the reason is the correct explanation of the assertion.