…………………………… prevents the entry of food in wind pipe.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Anatomy**: The human digestive system includes various structures that facilitate the process of digestion and the movement of food. The alimentary canal begins at the mouth and includes several parts such as the buccal cavity, pharynx, esophagus, and stomach.

2. **Identifying the Pharynx**: The pharynx is a crucial part of the digestive and respiratory systems. It serves as a common passage for both food and air. The pharynx connects the mouth to the esophagus (food pipe) and the trachea (windpipe).

3. **Recognizing the Role of the Epiglottis**: At the junction where the esophagus and trachea open into the pharynx, there is a structure called the epiglottis. The epiglottis is a flap of cartilage that plays a vital role in directing food away from the windpipe.

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