Trypsin and Elastase Are Both Enzymes That Catalyze Hydrolysis of Peptide

Multiple Choice

Trypsin and elastase are both enzymes that catalyze hydrolysis of peptide bonds. But trypsin only cuts next to lysine and elastase only cuts next to alanine. Why?

A) Trypsin is a protein, and elastase is not.
B) $\Delta$ G for the two reactions is different.
C) The shape of the active site for the two enzymes is different.
D) One of the reactions is endergonic, and the other is exergonic.
E) Hydrolysis of lysine bonds requires water; hydrolysis of alanine bonds does not.