This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'Disease highly transmitted during incubation period is - \nSelect and explain. \nA. Peussis, B. Cholera, C. Measles, D. Brucellosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Whooping cough is most infectious during the catarrhal stage. The infective period may be considered to extend from a weak after exposure to about 3 weeks after the onset of the paroxysmal stage although communicability diminishes rapidly after the catarrhal stage. (refer pgno:163 park 23 rd edition)', 'role': 'assistant'}]