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: Medicine
[{'content': '50 year old, Rishi has a diagnosis of pulmonary tuberculosis. How many infectious nuclei per cough are likely to be seen in sputum examination? \nSelect and explain. \nA. 1000, B. 2000, C. 3000, D. 4000', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Transmission of pulmonary TB to others is by droplet nuclei, which are aerosolized usually by coughing. The tiny droplets dry rapidly; the smallest (<5-10 m in diameter) may remain suspended in the air for several hours and may reach the terminal air passages when inhaled. There may be as many as 3000 infectious nuclei per cough. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 1342', 'role': 'assistant'}]