which observation in a rock layer would provide scientists with evidence that a mass extinction event had…

which observation in a rock layer would provide scientists with evidence that a mass extinction event had occurred? a. a rapid change in the features of fossilized species, and the discovery of new isotopes in fossils b. fossilized structures that are similar to those found in current organisms c. a gradual shift in the structures of fossilized organisms and the levels of uranium isotopes d. high levels of iridium (a metal found in asteroids) and a sudden lack of fossils of many species
Answer
Answer:
D. High levels of iridium (a metal found in asteroids) and a sudden lack of fossils of many species
Brief Explanations:
Iridium - rich layers are linked to asteroid impacts which can cause mass extinctions. A sudden lack of many species' fossils indicates a mass - die off.