Give the Final Step for the Mechanism for Glucose-6-Phosphate Isomerase

Multiple Choice

Give the final step for the mechanism for glucose-6-phosphate isomerase.

A) In the ring opening reaction,a base catalyst removes a proton from the OH group and an acid catalyst aids in the departure of the leaving group by protonating it.
B) A base catalyst removes a proton from the a-carbon of the aldehyde.
C) The enol is converted to a ketone.
D) The ester group is hydrolyzed.
E) The conjugate base of the acid catalyst and the conjugate acid of the base catalyst catalyze ring closure.