Which one is vestigial in humans ?

Options

A. Pinna muscles
B. Eye lids
C. Canine teeth
D. Nails.

Explanation

### Step-by-Step Solution:

1. **Understanding Vestigial Structures**: Vestigial structures are body parts that have lost their original function through the course of evolution. In humans, these are remnants of organs or structures that were functional in our ancestors but are no longer useful.

2. **Analyzing the Options**: The question provides four options to consider:
- A) Pinna muscle
- B) Eyelids
- C) Canine teeth
- D) Nails

3. **Evaluating Each Option**:
- **A) Pinna Muscle**: The auricular muscles (pinna muscles) are responsible for moving the ear in many animals, allowing them to better capture sounds. In humans, these muscles are largely non-functional and serve no significant purpose, making them vestigial.
- **B) Eyelids**: Eyelids protect the eyes from debris and help keep them moist. They serve an important function, so they are not vestigial.
- **C) Canine Teeth**: Canine teeth are used for tearing food, especially in carnivorous diets. They have a clear function in humans, so they are not vestigial.
- **D) Nails**: Nails protect the sensitive tips of fingers and toes and assist in gripping. They have a functional role, so they are not vestigial.

4. **Conclusion**: After evaluating all the options, the only structure that is considered vestigial in humans is the **pinna muscle**.

### Final Answer:
The vestigial structure in humans is the **pinna muscle**.

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