Final answer:
A) Pepsin functions optimally at a lower pH level than trypsin. Hence, A) is correct.
Step-by-step explanation:
The statement that most likely describes a difference in how pepsin and trypsin function is: A) Pepsin functions optimally at a lower pH level than trypsin.
Pepsin works best in the highly acidic environment of the stomach, with an optimum pH of about 1.5. In contrast, trypsin works in the small intestine, which is not as acidic, with an optimum pH of about 8.