This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory chain, Subject name: Biochemistry
Immediate energy supply for muscle contraction 
Select and explain. 
A. GTP, B. ATP, C. Creatine phosphate, D. Fatty acid
C: Creatine phosphate
Answer: C: Creatine phosphate 
Explanation: A Sprinter Uses Creatine Phosphate & Anaerobic Glycolysis to Make ATP, Whereas a Marathon Runner Uses Oxidative PhosphorylationCreatine Phosphate Constitutes a Major Energy Reserve in MuscleCreatine phosphate prevents the rapid depletion of ATP by providing a readily available high-energy phosphate that can be used to regenerate ATP from ADP.Creatine phosphate is formed from ATP and creatine at times when the muscle is relaxed and the demand for ATP is relatively low.The enzyme catalyzing the phosphorylation of creatine is creatine kinase (CK), a muscle-specific enzyme with clinical utility in the detection of acute or chronic diseases of muscle.Ref: Harper&;s biochemistry, 30th edition, page no: 676