This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vaccines, Subject name: Social & Preventive Medicine
[{'content': 'Efficacy of BCG vaccine for Pulmonary Tuberculosis \nSelect and explain. \nA. 0%, B. 25%, C. 33%, D. 50%', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Efficacy of BCG Vaccine 0-80% (0% for pulmonary TB) Average 50% (50% for severe forms of TB)', 'role': 'assistant'}]