Answer:
C. Prevents intestinal contents from backing up into the stomach
Explanation:
The pyloric sphincter is a muscle that is band shaped that is positioned at the base of the stomach between the pylorus (in stomach) and the duodenum (small intestine). Therefore not A or B, because this muscle is not associated directly to the esophagus.
This muscle plays its primary role in digestion of masticated food. Once a bolus has entered the stomach via the esophagus. This muscle acts a valve of sorts and controls how much chyme goes into the small intestine, it has relations only with the small intestine and not the large thus not D. Hence, the answer is C, which is true and fits all the functions of the pyloric sphincter.