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': 'Contacts of Sputum positive tuberculosis patient who should be given preventive chemotherapy \nSelect and explain. \nA. Children below 6 years, B. Old people, C. Children above 6 years, D. Pregnant women', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]