The Difference Between Direct and Indirect Immunofluorescence Testing Is That

The difference between direct and indirect immunofluorescence testing is that

A) Direct testing adds antibodies directly to antigens, whereas indirect testing cultures the organisms first and adds fluorescent tags to the patient sample.
B) Direct testing determines the identity of an unknown antibody in a patient sample, whereas indirect testing determines whether the patient is infected with a specific antigen.
C) Indirect testing determines the identity of an unknown antigen in a patient sample, whereas direct testing.determines whether the patient has been exposed to an antigen as evidenced by the presence of antibodies in their sera.
D) Direct testing determines the identity of an unknown antigen in a patient sample, whereas indirect testing.determines whether the patient has been exposed to an antigen as evidenced by the presence of antibodies in their sera.