![subject](/tpl/images/cats/biologiya.png)
2) We wish to test if a certain vaccine developed for a disease is effective or
not. What is the best way to do this?
A. Vaccinate 100 animals and expose all 100 to the disease.
B. Vaccinate 100 animals and expose 50 of them to the disease.
c. Vaccinate 50 animals, do not vaccinate 50 other animals, and expose all 1
to the disease.
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