Hexokinase catalyzes the reaction between glucose and ATP to form glucose 6-phosphate and ADP. The table below summarizes the results of experiments using purified hexokinase. In the experiments, different sugars were substituted for glucose, and the rate of each catalytic reaction was measured and divided by the rate of reaction using glucose as substrate. These data provide evidence for which general statement that has been made about enzymes?

Substrate Relative rate compared with using glucose as substrate

Glucose 1.0
Arabinose 0.1
Mannose 0.4
Galactose 0.02
Xylose 0.0

a. Enzymes are able to speed up a reaction by lowering its activation energy. b. Enzymes display high specificity with respect to their substrates. c. Enzymes often require cofactors and/or coenzymes in addition to their substrates. d. Enzymes bind substrates at their active sites using noncovalent forces of attraction. e. Enzymes lower activation energy of a reaction by stabilizing the substrate’s transition state.