If a person is infected with Salmonella typhi it can be confirmed by .

The correct option is D Widal test
A person infected with Salmonella typhi will suffer from typhoid. Typhoid fever is confirmed by Widal test. The serum sample of a typhoid patient has a high number of antibodies against Salmonella typhi antigens. This sample is added to Widal test suspension, which contains all Salmonella antigens in it. The antibodies bind to the antigens in the suspension, leading to agglutination. This agglutination means the patient is positive for Salmonella.