This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Concept of health and disease, Subject name: Social & Preventive Medicine
Under which level of prevention should sentinel surveillance be categorised 
Select and explain. 
A. Primordial prevention, B. Primary prevention, C. Secondary prevention, D. Teiary prevention
C: Secondary prevention
Answer: C: Secondary prevention 
Explanation: Sentinel surveillance is a method for identifying the missing cases and thereby supplementing the notified cases. it estimates disease prevalence in the total population. Repoing biases are minimised. It detects missing cases; so it comes under secondary prevention. Ref : Park&;s Textbook of Preventive and Social Medicine; 23rd edition - Pgno 40