Correct Option: B

The oral polio vaccine (OPV) was developed in 1961 by Albert Sabin. Also called “trivalent oral polio vaccine” or “Sabin vaccine”, OPV consists of a mixture of live, attenuated (weakened) poliovirus strains of all three poliovirus types. OPV produces antibodies in the blood to all three types of poliovirus. In the event of infection, these antibodies protect against paralysis by preventing the spread of wild poliovirus to the nervous system.