Pepsin, an enzyme found in the stomach, acts best at a pH of about 2, but it is not active at a pH of 7. Why?
A) The optimal pH helps to maintain the enzyme's tertiary structure.
B) The optimal pH helps to maintain the enzyme's primary structure.
C) The optimal pH disrupts the normal interactions of the R groups within the protein molecule.
D) A pH of 2 causes denaturation to occur but not at pH of 7.