Although the Gibbs Free Energy Change for the Reaction of Triose

Although the Gibbs free energy change for the reaction of triose phosphate isomerase is positive (+6.7 kj/mole) ,the reaction product (1,3-bisphosphoglycerate) is reduced to zero because

A) triose phosphate isomerase is written left to right.
B) triosephosphate isomerase is complexed to phosphoglycerate kinase,the next step in the sequence of reactions.
C) there are too few molecules of dihydroxyacetone phosphate available.
D) there are allosteric stimulants of triose phosphate isomerase.