The correct option is C Typhoid
Widal test is one of the methods that may be used to help make a presumptive diagnosis of enteric fever, also known as typhoid fever. It is caused by the bacterium Salmonella typhi. The Widal test relies on a reaction between antibodies present in the infected person's blood sample and specific antigens of S.typhi which produces clumping or agglutination that is visible to the naked eyes.
Therefore, the correct answer is option C.