4. Both water and glucose share an -OH that can serve as a substrate for a reaction with the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a million times more reactive as a substrate than water. The best explanation is that: (A) Glucose has more -OH groups per molecule than does water. (B) The larger glucose binds better to the enzyme; it induces a conformational change in hexokinase that brings active-site amino acids into position for catalysis. (C) The -OH group of water is attached to an inhibitory H atom, while the glucose -OH group is attached to С. (D) Water and the second substrate, ATP, compete for the active site resulting in a competitive inhibition of the enzyme. (E) Water normally will not reach the active site because it is hydrophobic.