What structure blocks food from entering the trachea during swallowing?

The epiglottis serves as a pivotal structure in the process of swallowing by preventing food and liquids from entering the trachea, which leads to the lungs. When a person swallows, the epiglottis is actively pulled down to cover the entrance of the trachea. This action effectively directs the food or liquid into the esophagus, ensuring that the airway remains clear and reducing the risk of aspiration, which can lead to choking or respiratory issues.

In the context of the anatomical process, the pharynx is involved in directing food toward the esophagus but does not have a protective role over the trachea during swallowing. The esophagus, meanwhile, is responsible for transporting food from the throat to the stomach but does not block anything from entering the trachea itself. Lastly, while the larynx is involved in voice production and is situated adjacent to the epiglottis, it does not function to prevent food from entering the trachea during swallowing. Therefore, the correct and most specific answer to the question is the epiglottis, which plays an essential and protective role during the swallowing process.