Ans. is 'b' i.e., Phosphoglycerate kinase o Irreversible steps are catalyzed by Glucokinase / Hexokinase, phosphofructokinase-I, and pyruvate kinase.o Reversible steps are catalyzed by Phosphohexose isomerase, aldolase, phosphotriose isomerase, glyceraldehyde 3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglycerate mutase, Enolase.o Usually 2 ATP molecules are formed in glycolysis by substrate level phosphorylation.o But, in Rapoport Leubering cycle (in RBC), production by substrate level phosphorylation from 1,3-BPG is bypassed by taking diversion pathway, i.e. side reaction of glycolysis. Thus, only 1 ATP is formed from fructose- 6-phosphate.o In this cycle, 1,3-BPG is converted to 23-BPG which is turn is converted to 3-phosphoglycorate.