All are true for the isomerase reaction of glucose-6-phosphate to fructose-6-phosphate except:
a. mg2 is required for activity.
b. it is an aldose to ketose isomerization.
c. "moving" the carbonyl from c-1 to c-2 creates a new primary alcohol group at c-1.
d. the reaction is irreversible with a large negative δg.