Select the correct statement with respect to diseases and immunisation
A. injection of snake antivenon against snake bite is an example of active immunisation.
B. It due to some reason B-and T-lymphocytes are damaged , the body will not produce antibodies against a pathogen.
C. Injection of dead/ inactivated pathogens causes passive immunity.
D. Certain protozeoans have been used to mass produce hepatitis B vaccine.