Which is not a vestigial part in humans ?

Options

A. Segmental muscles of abdomen
B. Finger nails
C. Third molar
D. Coccyx

Explanation

To determine which part is not a vestigial organ in humans, we need to understand what vestigial organs are and identify the options provided.

### Step-by-Step Solution:

1. **Understand Vestigial Organs**: Vestigial organs are those that have lost their original function through the course of evolution. They are remnants of organs that were fully functional in our ancestors.

2. **Identify Common Vestigial Organs in Humans**: Some well-known vestigial organs in humans include:
- The coccyx (tailbone)
- The third molars (wisdom teeth)
- The vermiform appendix
- Hair on the body
- Male nipples
- Auricular muscles (muscles around the ear)
- Nictitating membrane (a small fold of tissue in the inner corner of the eye)

3. **Evaluate the Options**: The question asks which part is not a vestigial organ. Among the options provided, we need to identify which one serves a current function in the human body.

4. **Identify the Non-Vestigial Organ**: Fingernails are not considered vestigial organs. They serve a protective function for the tips of our fingers and are fully functional. In contrast, the other options listed (like the coccyx, third molar, and others) are vestigial.

5. **Conclusion**: Based on the evaluation, the correct answer is that fingernails are not a vestigial part in humans.

### Final Answer:
Fingernails are not a vestigial part in humans.