The correct answer is b. Food is taken in via the mouth, where amylase is secreted by the salivary glands. Amylase helps the breakdown of sugars. After that, the food travels down to the esophagus, where it eventually enters the stomach. The parietal cells in the stomach secrete HCl, which is stimulates the breakdown of pepsinogen into pepsin. Pepsin is an enzyme that breaks down proteins. Following this step, the food then goes into the small intestine, specifically the duodenum. In the duodenum, the pancreas secretes many enzymes, like amylase, nucleases, lipase, and proteases, which all break down macromolecules into their monomers. Furthermore, here the gallbladder secretes bile in order to solubilize fats. After this, the digested food enters the colon of the large intestine, where water is absorbed.
Most of these questions come from our tutors, who are always looking for ways to get students more interested in the subject.