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
First case that comes to notice of physician is ? 
Select and explain. 
A. Primary case, B. Secondary case, C. Index case, D. Refer case
C: Index case
Answer: C: Index case 
Explanation: Ans. is 'c' i.e., Index case o Primary case --> First case of communicable disease introduced into the population. o Index case --> First case to come to attention of the investigator.