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': 'Most commonly used for protein utilization ? \nSelect and explain. \nA. NPU, B. Amino acid score, C. Biological value, D. Protein efficiency ratio', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is `a' i.e., NPU", 'role': 'assistant'}]