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': 'Parathormone secretion is stimulated by ? \nSelect and explain. \nA. Increased serum Ca++, B. Decreased serum Ca++, C. Increased serum K+, D. Decreased serum K+', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is `b' i.e., Decreased serum Ca++", 'role': 'assistant'}]