Fact 1: Passive immunity lasts only as long as the antibodies survive in body fluids. Fact 2: Booster shots are needed periodically to build up the passive immunity again. Given the two facts above, what are needed after antibodies won't survive in body fluids?
Pick from:
(a). booster shots;
(b). Veins and arteries.;
(c). chicken pox;
(d). Energy.;
(e). gun shots;
(f). kinetic energy;
(g). diseased tissue;
(h). turn to a doctor;
Answer:
(a).