The correct answer is (4) enzyme linked immunosorbent assay
The enzyme-linked immunosorbent assay (ELISA) is a test that uses antibodies and color change to identify a substance. Antigens from the sample are attached to a surface. Then, a further specific antibody is applied over the surface so it can bind to the antigen. This antibody is linked to an enzyme, and, in the final step, a substance containing the enzyme's substrate is added. The subsequent reaction produces a detectable signal, most commonly a color change in the substrate.
Uses of ELISA include:detection of Mycobacterium antibodies in tuberculosis
detection of rotavirus in feces
detection of hepatitis B markers in serum
detection of enterotoxin of E. coli in feces
detection of HIV antibodies in blood samples
