[A]: Homologous organs are similar in basic structure and embryonic origin, but serve dif- ferent functions.
[R]: Similarity in basic structure points to common ancestry whereas diversity in func- tion reflects adaptation to different modes of life.

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

### Step-by-Step Solution:

1. **Understanding Homologous Organs**:
- Homologous organs are defined as those that share a similar basic structure and embryonic origin but serve different functions in different organisms.
- Example: The forelimbs of humans and the front legs of a horse are homologous organs.

2. **Assertion Analysis**:
- The assertion states that "Homologous organs are similar in basic structure and embryonic origin but serve different functions."
- This statement is true because homologous organs indeed have a similar structure and origin while performing different roles in the respective organisms.

3. **Reason Analysis**:
- The reason provided states that "Similarity in basic structure points to common ancestry whereas diversity in function reflects adaptation to different modes of life."
- This statement is also true. The similarity in structure indicates that these organs have evolved from a common ancestor, while the differences in function suggest that these organs have adapted to meet the specific needs of different environments or lifestyles.

4. **Connecting Assertion and Reason**:
- The reason explains the assertion. The similarity in structure (common ancestry) and the diversity in function (adaptation) are directly related to the definition of homologous organs.
- Therefore, the reason is a correct explanation of the assertion.

5. **Conclusion**:
- Both the assertion and the reason are true, and the reason correctly explains the assertion. Thus, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation for the assertion.

### Final Answer:
- **Both Assertion and Reason are True; Reason is the Correct Explanation.**

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