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: Social & Preventive Medicine
[{'content': 'The milk of which of the following contains the least amount of calcium. \nSelect and explain. \nA. Human, B. Cow, C. Buffalo, D. Goat', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]