The activity of which cranial nerve can protect us by warning about harmful chemicals in the air ?

Options

A. V
B. IX & II
C. VI
D. X

Answer

To solve the question about which cranial nerve warns us about harmful chemicals in the air, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Cranial Nerves**: Understand that there are 12 pairs of cranial nerves, each with specific functions. The question provides options: 5th, 9th, 2nd, 6th, and 10th cranial nerves.

2. **Analyze Each Option**:
- **5th Cranial Nerve (Trigeminal Nerve)**: This nerve is responsible for sensation in the face and motor functions such as biting and chewing. It is also involved in detecting irritants in the nasal and oral cavities.
- **9th Cranial Nerve (Glossopharyngeal Nerve)**: This nerve is primarily involved in swallowing and the gag reflex.
- **2nd Cranial Nerve (Optic Nerve)**: This nerve is responsible for vision.
- **6th Cranial Nerve (Abducens Nerve)**: This nerve controls the lateral movement of the eye.
- **10th Cranial Nerve (Vagus Nerve)**: This nerve has various functions, including motor and sensory functions in the throat and organs in the chest and abdomen.

3. **Determine the Correct Answer**: The trigeminal nerve (5th cranial nerve) is specifically responsible for warning us about harmful chemicals in the air by providing sensations of chemical irritants. Therefore, the correct answer is the **5th cranial nerve**.

4. **Conclude**: The activity of the trigeminal nerve protects us by warning about harmful chemicals in the air.

### Final Answer:
The activity of the **5th cranial nerve (Trigeminal Nerve)** can protect us by warning about harmful chemicals in the air.

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