Which statement best describes the breakdown of food in the digestive system?

The accurate response is option B: Carbohydrate digestion commences in the mouth, whereas protein breakdown begins in the stomach.

The second option is correct. Carbohydrate digestion initiates in the mouth, while protein digestion begins in the stomach. Specifically, carbohydrate breakdown starts in the mouth through mechanical chewing and the enzyme salivary amylase present in saliva. In contrast, protein digestion takes place in the stomach where enzymes such as pepsin (from the stomach), trypsin, and chymotrypsin (from the pancreas) act to decompose the food proteins into polypeptides and progressively into amino acids.