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
In epidemic, 1st step is: 
Select and explain. 
A. Verification of diagnosis, B. Isolation, C. Immunization, D. Notification
A: Verification of diagnosis
Answer: A: Verification of diagnosis 
Explanation: Verification of diagnosis