Answer: D.enzyme
Step-by-step explanation:
The enzymes are the macromolecules which functions as catalysts in the chemical reactions occurring in the biological systems. The enzymes speed up the reaction. The molecules over which the enzymes act are called as the substrates and these substrates are covered by the enzymes into products.
Lactase is an enzyme which is located in the borders of the small intestine of humans and animals. The function of lactase is to conduct the complete digestion of lactose into sugar, the sugar is the simple substance which a body can digest easily.
Carbonic anhydrase is the enzyme that causes the inter-conversion of substrates like carbon dioxide and water into carbonic acid, bicarbonate ions and protons.