Answer: The correct answer is  D) The epiglottis closes the air pathway so that food will not enter it.

The pharynx is the structure in the throat which serves as a pathway of both air and food. The epiglottis ( located on the top of the larynx) is a cartilaginous flap which constantly moves back and forth in order to prevent the entry of food into the lungs.  

When we swallow food, the epiglottis closes the air pathway by covering the larynx ( voice box), which is part of the respiratory system. This allows the food to enter in the esophagus and prevent from entering it in the windpipe.

Thus, the epiglottis closes the air pathway so that food will not enter it.