<span>Pavlov became interested in studying reflexes when he saw that the dogs drooled without the proper stimulus. Although no food was in sight, their saliva still dribbled. It turned out that the dogs were reacting to lab coats.</span>May 15, 2001
Answer:
The correct answer is herd immunity
Explanation:
Herd immunity is a type of immunity provided by the major population which is vaccinated or immune against an infectious to some individual of their community which is not immune to that infection.
Herd immunity is generated only when most of the population is immune to that particular disease. For example, in measles, 90-95% of a population should be vaccinated against measles to provide herd immunity to the un-immune individuals. So the correct answer is herd immunity.
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Hope this helps xox :)