Answer:
The best way to test the effectiveness of a vaccine against a disease is vaccinate 50 animals, do not vaccinate 50 other animals, and expose all 100 to the disease (option C).
Explanation:
When testing a vaccine for effectiveness, the option is to <u>administer the vaccine to half of the population exposed to a </u><u>disease</u>, since effectiveness should measure the performance of the vaccine within a community.
If there are 100 animals exposed to a disease, the fact that the 50 vaccinated animals do not get sick is an excellent test of how the vaccine works and what its effectiveness is.
The other 50 animals, not vaccinated, would act as a control group exposed to the same disease and sharing a certain space.
The other options are not correct because:
<em> A. Vaccinating the 100 exposed animals does not provide an unvaccinated control group to compare the effects of the vaccine.
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<em> B. Vaccinating all 100 animals and exposing only 50 to the disease does not make sense, since it would not be possible to measure effectiveness in vaccinated animals that are not exposed.
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<em> D. Vaccinating 50 animals and not vaccinating the other 50 to expose only the vaccinated animals to the disease does not make sense since the conditions of the test group and the control group should be the same.</em>
