The answer is
C. periodic fluctuations in the intensity if sound waves.
1)Food is crushed and ground in the mouth by teeth
2)Chewed food is pushed into the pharynx
3)Food enters the esophagus
4)Food passes through a valve and into the stomach
5)Food is broken down by pancreatic enzymes and absorbed by the small intestine
6)Undigested material is pushed into the large intestine
7)Waste material is compressed in the rectum and eliminated through the anus
