`"_____________"` prevents passage of food into trachea.

Answer

To answer the question, "_____________" prevents the passage of food into the trachea, we need to identify the structure responsible for this function. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding the Trachea**: The trachea is a vital part of the respiratory system, acting as the windpipe that carries air to and from the lungs.

2. **Identifying the Junction**: The trachea is located behind the esophagus (the food pipe) in the neck region. At the junction where the trachea and esophagus meet, there is a structure known as the glottis.

3. **Role of the Epiglottis**: The epiglottis is a flap-like structure situated above the glottis. Its primary function is to act as a lid that covers the glottis during swallowing.

4. **Mechanism During Swallowing**: When food is swallowed, the epiglottis folds down over the glottis, effectively blocking the entrance to the trachea. This prevents food from entering the trachea and ensures that it goes down the esophagus into the stomach.

5. **Importance of the Epiglottis**: This mechanism is crucial for preventing choking and ensuring that food does not enter the lungs, which could lead to serious health issues.

6. **Conclusion**: Therefore, the correct answer to the question is "epiglottis."

### Final Answer:
**Epiglottis** prevents the passage of food into the trachea.

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