Correct Answer: to detect antibodies and hormones present in the blood samples

Solution : The correct option is to detect antibodies and hormones present in the blood samples.

Radioimmunoassay (RIA) is a laboratory technique used for measuring the concentration of specific substances in biological samples, such as blood, urine, or tissue. RIA is primarily employed in medical diagnostics and research to detect and quantify hormones, drugs, proteins, antibodies, and various other molecules in the body. RIA relies on the use of radioactive isotopes (usually iodine-125) to label specific molecules of interest, such as hormones or antibodies.