The correct answer is option 2: Pepsin. Pepsin is an enzyme that is primarily found in the stomach and is responsible for the digestion of proteins. It is produced in the gastric chief cells as the inactive precursor pepsinogen, and then activated by the acidic environment of the stomach.
Option 1: Trypsin is an enzyme that is produced in the pancreas and helps in the digestion of proteins in the small intestine. It does not function in the stomach.
Option 3: Lipase is an enzyme that helps in the digestion of fats. It is produced in the pancreas and works in the small intestine, not in the stomach.
Option 4: Amylase is an enzyme that helps in the digestion of carbohydrates. There are two types of amylase, salivary amylase produced in the mouth, and pancreatic amylase produced in the pancreas. Neither of these enzymes function in the stomach.
Therefore, the correct enzyme that can hydrolyse proteins in the stomach is Pepsin.