A researcher added a mixture of animal proteins to a physiological bufler solution (pH 7.4) in a test tube incubated at 37"C.
The researcher then added purified pepsin to the mbture, but even after several hours, the proteins were not digested.

Which of the following would explain this result?

a)Pepsin must be converted to its active form, pepsinogen, which digests proteins.

b)The pH was too high

c)Pepsin doesn't digest animal proteins

d)The temperature was too low