Which of the following reactions isunique to the process of glycolysis?
           a.        fructose-1,6-bisphosphate ====> glyceraldehyde-3-phosphate +   dihydroxyacetone phosphate
           b.        2-phosphoglycerate =====> 3-phosphoglycerate
           c.        glucose-6-phosphate =====> fructose-6-phosphate
           d.        phosphoenolpyruvate =====> pyruvate
