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': 'What is the first case of a paicular condition that comes to notice of a physician termed as? \nSelect and explain. \nA. Primary case, B. Secondary case, C. Index case, D. Refer case', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Index case is the first case that comes to the attention of the investigator. Case is defined as a person in the population or study group identified as having the paicular disease, health disorder or condition under investigation. - Primary case: It is the first case of a communicable disease introduced into the population unit being studied. - Secondary case: are those developing from contact with a primary case.', 'role': 'assistant'}]