Assertion :

Typhoid is an acute infectious disease caused by Salmonella typhi which is found in human intestine.

Reason: Typhoid is diagnosed by Widal test

The correct option is B if both Assertion and Reason are true but Reason is not the correct explanation of Assertion
Typhoid is an acute infectious disease caused by Salmonella typhi. Typhoid spreads through food, milk and water contaminated with intestinal discharges either directly or through flies and faulty personal hygiene. Main symptoms are high fever, headache, diarrhea, gastrointestinal disorders like ulceration of intestine etc. Typhoid is diagnosed by Widal test, an agglutination test-for the presence of antibodies against the Salmonella organisms that cause typhoid fever. So, the correct answer is 'if both Assertion and Reason are true but Reason is not the correct explanation of Assertion'.