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': 'A unit of mass equal to one twelfth the mass of an atom of carbon-12 is known as: \nSelect and explain. \nA. Mole, B. Dalton, C. Equivalent, D. None of the above', 'role': 'user'}, {'content': "Answer: B \nExplanation: The molecular weight of a substance is the ratio of the mass of one molecule of the substance to the mass of one twelfth the mass of an atom of carbon-12. Because molecular weight is a ratio, it is dimensionless. The dalton (Da) is a unit of mass equal to one twelfth the mass of an atom of carbon-12. Ref: Ganong's Review of Medical Physiology 23rd edition, Chapter 1.", 'role': 'assistant'}]