33. Which of the following four statements regarding glycolysis and gluconeogenesis is correct ? (1) Substrate-level phosphorylation occurs when conversion of1,3-bisphosphoglycerate to 3-phosphoglycerate occurs. (2) The only oxidative reaction in glycolysis is the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate. (3) The phosphofructokinase-1 catalyzes the glycolytic reaction step that is irreversible in gluconeogenesis. (4) If fructose-2,6-bisphosphate is low, glycolysis proceeds； if fructose-2,6-bisphosphate is high, gluconeogenesis proceeds. (A) (1), (2), and (4) are correct. (B) (1), (3), and (4) are correct. (C) (1), (2), and (3) are correct. (D) (2), (3), and (4) are correct. (E) All are correct.