This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Muscle Physiology, Subject name: Physiology
[{'content': 'Which one of the following acts to increase the release of Ca2+ from endoplasmic reticulum \nSelect and explain. \nA. Inositol triphosphate, B. | Parathyroid hormone, C. 1,25 - dihydroxy choleciferol, D. Diacyglycerol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Inositol triphosphate(Ref: Ganong, 25th ed/p. 116)Inositol triphosphate acts on the sarcoplasmic reticulum to release calcium ions', 'role': 'assistant'}]