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': 'The most significant immediate result of lowered serum calcium is \nSelect and explain. \nA. Weakened heart action, B. Decalcification of bones, C. Decalcification of teeth, D. Hyperirritability of nerves and muscles', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]