Question

for an enzyme to be able to catalyze a reaction, the active site must-
o be occupied by an inhibitor
o increase the activation energy level
o have a complementary shape to the substrate
o cause the enzyme to be destroyed in the reaction

Explanation:

Enzymes work based on the lock - and - key model or induced - fit model. For an enzyme to catalyze a reaction, its active site must have a complementary shape to the substrate to bind with it effectively. An inhibitor binding to the active site would prevent the reaction. Enzymes lower activation energy, not increase it. Also, enzymes are not destroyed in the reaction as they are catalysts.

Answer:

have a complementary shape to the substrate