Which of the following enzymes breaks down complex carbohydrates?

Amylase is the enzyme responsible for breaking down complex carbohydrates into simpler sugars. It initiates the process of starch digestion, which occurs primarily in the mouth through saliva and continues in the small intestine. Amylase works by hydrolyzing the glycosidic bonds in starch and glycogen, converting these polysaccharides into maltose and dextrins, which can then be further digested into glucose.

In contrast, the other enzymes listed have specific roles that do not involve carbohydrate breakdown. Pepsin is primarily involved in protein digestion in the stomach, targeting peptide bonds in proteins. Lactase is the enzyme that breaks down lactose, the sugar found in milk, but it specifically acts on a disaccharide rather than complex carbohydrates. Lipase is responsible for breaking down fats into fatty acids and glycerol, playing no role in carbohydrate digestion. Thus, amylase is distinctly the enzyme that acts on complex carbohydrates, making it the correct choice.