Which Factor Contributes to the Catalytic Activity of Enzymes

Multiple Choice

Which factor contributes to the catalytic activity of enzymes?

A) Reacting groups are brought together at the active site in the proper orientation.
B) Amino acid side chains serve as catalysts.
C) Metal ions in the active site act as catalysts.
D) Amino acid side chains stabilize transition states and intermediates.
E) all of the above