The correct answer is c) oral cavity and stomach.
Chemical digestion of carbohydrates begins in the oral cavity. Saliva contains an enzyme called amylase that starts breaking down starches into simpler sugars as soon as food enters the mouth. This process continues until the food reaches the stomach.
On the other hand, the chemical digestion of proteins begins in the stomach. The stomach secretes gastric juices, which contain hydrochloric acid and the enzyme pepsin. These substances work together to denature proteins and break them down into smaller peptides.
In summary, carbohydrates undergo initial chemical digestion in the oral cavity, while proteins start their chemical digestion once they enter the stomach.