the structure which prevents the entry of food into respiratory tract is

Options

A. Glottis
B. Pharynx
C. Epiglottis
D. Larynx

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the structure that prevents food from entering the respiratory tract. This involves identifying the relevant anatomical structures involved in the digestive and respiratory systems.

2. **Evaluating the Options**:
- **Glottis**: The glottis is part of the larynx that consists of the vocal cords. It does not play a role in preventing food from entering the respiratory tract. Therefore, this option is incorrect.

- **Pharynx**: The pharynx, commonly known as the throat, serves as a passageway for both air and food. While it is involved in both respiratory and digestive functions, it does not specifically prevent food from entering the respiratory tract. Thus, this option is also incorrect.

- **Epiglottis**: The epiglottis is a flexible flap located at the superior end of the larynx. Its primary function is to act as a switch between the larynx and the esophagus. When swallowing, the epiglottis folds down to cover the larynx, preventing food from entering the airway and directing it into the gastrointestinal tract. This makes the epiglottis the correct answer.

- **Larynx**: The larynx, also known as the voice box, is involved in breathing and sound production but does not specifically prevent food from entering the respiratory tract. Therefore, this option is incorrect.

3. **Conclusion**: After evaluating all the options, the structure that prevents the entry of food into the respiratory tract is the **epiglottis**.

### Final Answer:
The structure which prevents the entry of food into the respiratory tract is the **epiglottis**.

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