Final answer:
The lowermost portion of the pharynx is the laryngopharynx, which serves as a common pathway for air and food and connects to the larynx and esophagus.
Step-by-step explanation:
The lowermost portion of the pharynx is referred to as the laryngopharynx. This region of the pharynx is bordered by the oropharynx superiorly and the esophagus and trachea inferiorly. It serves as a route for both air and food. The laryngopharynx is responsible for continuing the route for ingested material and air until its inferior end, where the respiratory system and the digestive system diverge. The stratified squamous epithelium of the oropharynx is continuous with that of the laryngopharynx; anteriorly it opens into the larynx, and posteriorly it enters the esophagus. Hence, the correct answer to the question about the lowermost portion of the pharynx is c. Laryngopharynx.