How does the activation of pepsinogen in the stomach illustrate the role of zymogens in digestion?

• A. Pepsinogen is activated by a decrease in temperature in the stomach.
• B. Pepsinogen is activated by binding to carbohydrates in the stomach.
• C. Pepsinogen is activated by the presence of lipids in the stomach.
• D. Pepsinogen is activated to pepsin in the acidic environment of the stomach, aiding in protein digestion.

Answer: (D)