Which structure prevents food from entering the trachea during swallowing?

The epiglottis is a flap-like structure located at the entrance of the larynx, which plays a critical role in the swallowing process. During swallowing, the epiglottis folds down over the trachea (windpipe) to prevent food and liquid from entering the airway. This action ensures that the food is directed into the esophagus, which leads to the stomach, rather than into the respiratory tract. This protective mechanism is essential for preventing choking and ensuring that the respiratory system remains clear of food particles.

The larynx, while involved in voice production and protecting the airway during breathing, does not actively prevent food from entering the trachea. The pharynx serves as a passageway for both air and food but does not directly prevent food from entering the trachea. The esophagus is the tube that carries food to the stomach but has no role in blocking the trachea during swallowing. Thus, the epiglottis is the correct answer as it directly fulfills the function of safeguarding the airway during the swallowing process.