Apatient with high blood pressure who is otherwise healthy is counseled to restrict sodium intake. this is an example of a. primary prevention. b. secondary prevention. c. tertiary prevention. d. disease treatment.

The answer is b. secondary prevention. 
Secondary prevention tries to prevent a disease before it fully develops . While primary prevention is done for the diseases a person is suffering from in present the secondary prevention is done for the diseases which might happen to affect in future.These are not only preventive measures but also intervening measures taken to halt the development of disease.