Correct Answer - D
ELISA (Enzyme Linked Immuno Sorbent Assay), also known as an Enzyme Immuno Assay (EIA), is a biochemical technique used mainly in immunology to detect the presence of an antibody or an antigen in a sample
It is a useful tool for determining serum antibody concentrations (such as with the HIV test). The ELISA was the first screening test widely used for HIV because of its high sensitivity as it detects antibodies at very low concentrations
