Which is done even after control of disease?

Ans: A (Surveillance) Ref: Park v Preventive and Social Medicine, 22nd edition. Pg 118Explanation:Surveillance is continuous scrutiny of occurrence of disease or health related events to take action.So, even after control of disease, one needs to keep an eye on the occurrence of disease, so that it is identified in time to take action.All other options are distracters.