Glucokinase has a K_m value of 10.0 mM, whereas hexokinase has a K_m value of 0.1 mM. This is consistent with which of the following?

A) glucokinase acts on glucose at low concentrations.
B) glucokinase acts on glucose only at high glucose concentrations.
C) glucokinase phosphorylates most of the glucose at low glucose levels.
D) hexokinase acts on glucose only at high levels of glucose.
E) hexokinase acts at about half-maximal velocity at glucose concentrations of 4-5 mM.