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': '. The following set of words can be used synonymously in epidemiology - \nSelect and explain. \nA. Source and Reservoir, B. Index and primary case, C. Latent infection and subclinical infection, D. Serial interval and incubation period', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]