For each of the following reactions described below, identify a corresponding step of glycolysis.
a) ____ Phosphorylation of glucose to produce glucose-6-phosphate.
b) ____ Formation of a hexose phosphate from a hexose.
c) ____ An oxidation reaction is catalyzed by glyceraldehyde-3-phosphate dehydrogenase.
d) ____ Phosphorylation of fructose-6-phosphate to produce fructose-1,6-bisphosphate.