Rings of cartilage in the throat prevents :

Options

A. Collapsing of air passage.
B. Entering of food in air pipe.
C. Bacterial infection in the tract
D. Entering of microbes.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Structure**: The throat contains two main tubes: the trachea (air passage) and the esophagus (food pipe). The trachea is supported by rings of cartilage.

2. **Function of Cartilage Rings**: The rings of cartilage provide structural support to the trachea. They keep the airway open and prevent it from collapsing, especially when air pressure decreases.

3. **Analyzing the Options**:
- **Option 1**: Collapsing of air passage - This is correct because the cartilage rings prevent the trachea from collapsing.
- **Option 2**: Entry of food in air pipe - This is incorrect as the cartilage does not prevent food from entering the trachea; rather, it is the epiglottis that prevents this.
- **Option 3**: Bacterial infection in the tract - This is also incorrect; the rings of cartilage do not prevent bacterial infections.
- **Option 4**: Entering of microbes - This is incorrect for the same reason as above.

4. **Conclusion**: The correct answer is that the rings of cartilage in the throat prevent the collapsing of the air passage.

**Final Answer**: Rings of cartilage in the throat prevent the collapsing of the air passage.

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