This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Muscle, Subject name: Physiology
Least useful for a 800-m run in a competitive event would be 
Select and explain. 
A. Oxidative phosphorylation, B. Pale muscle fibres, C. Lohmann reaction, D. Muscle glycogen
A: Oxidative phosphorylation
Answer: A: Oxidative phosphorylation 
Explanation: 800-m run would be over in about 2 min, and it would need a quick burst of activity of the muscle rather than a slow and sustained activity for prolonged periods. Option A: Oxidative phosphorylation generates ATPs in a slow and sustained manner for a low-intensity muscular activity that continues for prolonged periods (e.g., marathon). It will be the least useful of the energy systems for a sho-time event like 800-m run. Option C: LOHMANN REACTION: CREATINE PHOSPHATE - ADP - ATP - UTILIZED For such sho-duration intense muscular activity, pale fibers are more useful as they generate quick ATPs anaerobic glycolysis, using muscle glycogen as the source. Thus, options B and D are useful.