[A]: Presence of tail in children is a vestigial character.
[R]: This is due to the phenomenon called atavism

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 the Assertion (A)**: The assertion states that the presence of a tail in children is a vestigial character.
- **Explanation**: A vestigial character is an organ or body part that has lost most or all of its original function through the course of evolution. In humans, examples include the tailbone, wisdom teeth, and the appendix.

2. **Defining Vestigial Characters**: Vestigial characters are remnants of features that served a purpose in the organism's ancestors but are no longer functional in the current form.
- **Examples**: In humans, the tailbone is a remnant of a tail that our ancestors had.

3. **Understanding the Reason (R)**: The reason provided states that the presence of a tail in children is due to a phenomenon called atavism.
- **Explanation**: Atavism refers to the reappearance of traits from an ancestral lineage that have been absent for several generations. This can occur when certain genes that were dormant or suppressed become active again.

4. **Connecting A and R**: The assertion is that the tail is a vestigial character, while the reason explains that the appearance of a tail in children can be attributed to atavism, which is the re-emergence of ancestral traits.
- **Conclusion**: Both the assertion and the reason are true, and the reason provides a correct explanation for the assertion.

5. **Final Answer**: Therefore, the correct conclusion is that both A and R are true, and R is the correct explanation for A.

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