The correct answer is:
Peristalsis (C.)
Explanation:
Peristalsis is an involuntary movement that results in a radially symmetrical wavelike movement down a tubular structure, notably the human digestive tract. Here, the wave of progressive contraction and relaxations of the longitudinal and circular muscles helps to transport the food (bolus) from one point in the tube to another. It occurs in the esophagus, stomach and intestines.
esophagus: It takes approximately 9 seconds for the wave to travel the length of the tube. Peristalsis occurs in other animals too, especially in curd-chewing ruminants, where reverse-peristalsis causes food to be moved from the stomach back to the mouth for re-chewing, this is usually not possible in humans because peristalsis is weak compared to other animals.
small intestine: one food is processed and digested in the small intestine, the chyme produced is passed into the small intestine through the pyloric sphincter. The presence of chyme in the small intestine initiates peristaltic motion, which occurs in both direction and as a normal response, the body inhibits the motion in towards the oral direction. The peristaltic motion in the small intestine is mostly to mix the content of chyme and and facilitate digestion, but in the process, the food makes its way into the large intestine.
large intestine: here, general contractions, also called mass movements occurs 1-3 times per day, moving the feces now produced into the rectum for expulsion.
Peristalsis also occur in the movement of lymph and sperm though their respective tubules. It is also worthy of note that during vomiting, reverse peristalsis does not occur in the esophagus as commonly believed, instead, it is brought about by a forced contraction in the abdominal region.
