Rennin is primarily important for digesting which in infants?

• A. Fats
• B. Carbohydrates
• C. Proteins
• D. Milk

Answer: (D)

Rennin helps infants digest milk by coagulating the milk proteins. It acts specifically on casein in milk, turning liquid milk into a soft curd. This curd formation slows gastric emptying and gives the infant’s still-developing digestive system time to break down the proteins with enzymes like pepsin. Because the enzyme’s role is tied to milk protein in the milk itself, it’s not about fats or carbohydrates, and it doesn’t broadly digest proteins in general—its action is on the milk protein casein. So the primary importance is digesting milk.