Which of the following is not an example vestigeal organ humans?

Options

A. Muscles of external ear
B. Nictitating membrane of eye
C. Appendix of caecum
D. Second molar teeth

Answer

To solve the question of which of the following is not an example of a vestigial organ in humans, we can follow these steps:

### Step 1: Understand the concept of vestigial organs
Vestigial organs are body parts that have lost their original function through the course of evolution. They may still be present in the body but serve little or no purpose in the current context.

### Step 2: Identify examples of vestigial organs in humans
Some commonly recognized vestigial organs in humans include:
- **Wisdom Teeth**: These were useful for our ancestors who consumed raw food but are largely unnecessary today.
- **Pinna (External Ear Muscles)**: These muscles are not used for moving the ears as they were in some animals.
- **Nictitating Membrane**: This is a remnant from our ancestors, which is no longer functional as we have eyelids.
- **Appendix**: Once thought to aid in digestion of raw food, it is now considered vestigial.

### Step 3: Analyze the options given in the question
From the context provided, we need to determine which option does not represent a vestigial organ. The options mentioned include:
1. Wisdom Teeth (vestigial)
2. Pinna (vestigial)
3. Nictitating Membrane (vestigial)
4. Second Molar Teeth (not vestigial)

### Step 4: Determine the correct answer
The second molar teeth are still functional and play a role in the mastication of food. Therefore, they are not considered vestigial organs.

### Conclusion
The answer to the question "Which of the following is not an example of a vestigial organ in humans?" is **Second Molar Teeth**.

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