Fumarase is the enzyme that catalyzes the following reaction between fumarate and water to produce malate in cells. Which statement can be used as evidence that orientation of reactant molecules is part of the function of fumarase as a catalyst?

a. The active site of fumarase contains a histidine and a lysine that function as an acid and a base, respectively, during catalysis.

b. Fumarase does not use a coenzyme but requires one Fe2+ ion at its active site.

c. Fumarase binds one fumarate molecule and one water molecule the same way for every reaction.

d. Mutation of the active site lysine to other amino acids obliterates or severely reduces activity in fumarate.

e. Fumarase catalyzes both the forward and reverse reactions between fumarate and malate.