How do index fossils scientists?
they aid in the study of ranges of different organisms.
they advance understanding of the origin of life on earth.
they aid in comparison of rock layers at distant locations.
they advance understanding of rock type at the time the organism lived.

index fossils are important for index fossils because

they use them to match up rock layers in certain locations

that may be far apart!

So I think it's C

because of

i think that is new experiments yield untrustworthy data and should be carefully considered, because you don't know what will happen with the experiments.