Which one of the following is an enzyme ?

The correct answer is C. Trypsin.

An enzyme is a biological catalyst, a substance that increases the rate of a chemical reaction

without itself undergoing any permanent chemical change. Almost all metabolic processes in the cell need enzymes in order to occur at rates fast enough to sustain life.

Gastrin is a

hormone that stimulates the secretion of gastric acid and pepsin from the stomach.

Keratin is a structural protein found in hair, nails, and skin.

Vasopressin is a hormone that helps to regulate blood pressure and water balance.

Trypsin is a digestive enzyme that breaks down proteins into smaller peptides. It is produced in the pancreas and secreted into the small intestine.