What digestive substances are bound to the microvilli of columnar epithelial cells of the small intestine?

It is the border brush enzyme.

Border brush enzymes are hydrolytic enzymes bound to the microvilli of columnar epithelial cells of the small intestines. They are produced by pancreas, and are ducted by main pancreatic duct. They are responsible for the final and terminal stage of digestion of dietary carbohydrates and proteins. They transport the resulting amino acids and sugars into the epithelial cells.

The answer would be c