Answer:
C
Explanation:
Becuase fom a vaccine you are recieving antibodies by another animal or human donor.
D is unlinkely since it describes how the mother is nursing the baby, so nothing directly mentioning of the baby recieving any antibodies. The other options also talk about how the body creates its own antibodies, which isn't passive immunity.
Answer:
Certain fossils, called index fossils, help geologists match rock layers. To be useful as an index fossil, a fossil must be widely distributed and represent a type of organism that existed for a brief time period. Index fossils are useful because they tell the relative ages of the rock layers in which they occur.
The purpose of an experiment is to compare results with others.
