Q: Fact 1: Passive immunity lasts only as long as the antibodies survive in body fluids. Fact 2: Inside the body, blood is normally a fluid. Given the two facts above, passive immunity lasts only as long as the antibodies survive where?

OPT: I. cows. II. heat. III. skin. IV. Mitosis. V. blood. VI. humans. VII. Summer. VIII. animals.
A:
V.