4. 下列哪一個步驟是不可逆的速率限制步驟? (5%)(A) Glucose → Glucose-6-phosphate(B)Fructose-6-phosphate→ Fructose-1,6-bisphosphate(C) Pyruvic acid Lactic acid(D) Glyceraldehyde-3-phosphate - 1,3-bisphosphoglyceric acid