This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Skeletal muscle contraction ends when: \nSelect and explain. \nA. Ions move out of cytoplasm, B. Ach is absorbed from the NMJ, C. Closure and in\xaddrawing of receptors, D. Decreased calcium outside reticulum', 'role': 'user'}, {'content': 'Answer: D \nExplanation: “Once the Ca2+ concentration outside the reticulum has been lowered sufficiently, chemical interaction between myosin and actin ceases and the muscle relaxes.”', 'role': 'assistant'}]