The third eyelid in frog is called

Options

A. Pineal eye
B. Nictitating membrane
C. Lower eyelid
D. Upper eyelid

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name of the third eyelid in frogs.

2. **Identifying the Eyelids in Frogs**: Frogs have three eyelids:
- The **lower eyelid**: This is thin and unmovable.
- The **upper eyelid**: This is thicker and movable.
- The **third eyelid**: This is the one we need to identify.

3. **Describing the Third Eyelid**: The third eyelid in frogs is known as the **nictitating membrane**.

4. **Function of the Nictitating Membrane**: This membrane is semi-transparent and serves important functions:
- It allows frogs to see underwater.
- It helps in protecting the eye and provides a defense mechanism against predators.

5. **Eliminating Other Options**:
- The **lower eyelid** is thin and unmovable, so it cannot be the third eyelid.
- The **upper eyelid** is thicker and movable but is not the third eyelid.
- The **pineal eye** is not related to the eyelids and is a different structure altogether.

6. **Conclusion**: Therefore, the third eyelid in frogs is called the **nictitating membrane**.

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