The Mg²⁺ Metal Ions Involved in the Enolase Reaction Mechanism

The Mg²⁺ metal ions involved in the enolase reaction mechanism are required for which reason?

A) They form covalent bonds with a porphoryin ring to coordinate the substrate.
B) They enhance the electron-withdrawing potential of the carbonyl group of 2-phosphoglycerate.
C) They stabilize the phosphate group of 2-phosphoglycerate.
D) They allow a Lys in the active site to donate a proton to the 2-phosphoglycerate substrate.
E) They prevent the reverse catalysis of 3-phosphoglycerate to 2-phosphoglycerate from taking place.