What role does the coenzyme A portion of acetyl-CoA play in the reaction catalyzed by citrate synthase?

A)the CoA group causes the enzyme to close around the substrates,enabling catalysis
B)lack of resonance in the thioester makes the methyl carbon of the acetyl group more acidic,allowing proton abstraction to readily occur
C)CoA makes the carbonyl carbon highly susceptible to nucleophilic attack
D)hydrolysis of the thioester makes the reaction essentially irreversible
E)all of the above