Which of the Following Is Not True of Vitamin B₁₂

Which of the following is not true of vitamin B₁₂?

A) Enzymes that catalyze some isomerization reactions require coenzyme B₁₂.
B) People must obtain vitamin B₁₂ from their diets.
C) Coenzyme B₁₂-requiring enzymes generally catalyze reactions through a cationic process.
D) Coenzyme B₁₂ is required by enzymes that catalyze the exchange of a hydrogen bonded to one carbon with a group bonded to an adjacent carbon.
E) The chemistry of coenzyme B₁₂ takes place at the bond joining the cobalt and the 5?-deoxyadenosyl group.