Correct Answer - C
The Enzyme Linked Immuno Sorbent Assay (ELISA), also known as the Enzyme Immuno Assay (EIA) has become a widely used serological techmque for. detection of AIDS in the blood serum of HIV infected person. The enzymes used for labelling in ELISA include horse radish peroxidase, alkaline phosphatase, `beta`-galactosidase, lactoperoxidase, etc.