This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: obstetrics,pediatrics and geriatrics, Subject name: Social & Preventive Medicine
[{'content': 'Present in human milk \nSelect and explain. \nA. CaCO3, B. Ca & P, C. K lactate, D. None', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ref:Park's Text book of Preventive and Social Medicine 25th ed", 'role': 'assistant'}]