Question

1. which statement best describes how scientists can use evidence from rock layers to construct a timeline of earth’s history? (seen)

a scientists can look for marine and land fossils in the same rock layer.
b scientists can match commonly found fossils from organisms that lived during many time periods.
c scientists can use index fossils and radioactive dating of rock layers to place events in order.
d scientists can study magma at underwater valleys to determine when the oldest organisms first appeared.

Explanation:

• Option A: Marine and land fossils in the same rock layer is unlikely as environments differ, so A is incorrect.
• Option B: Index fossils (used for dating) are from organisms with short - lived, widespread existence, not those living in many time periods. So B is wrong.
• Option C: Index fossils help correlate rock layers, and radioactive dating gives absolute ages. Together, they help construct Earth's history timeline. This is correct.
• Option D: Studying magma at underwater valleys doesn't relate to dating the oldest organisms. So D is incorrect.

Answer:

C. Scientists can use index fossils and radioactive dating of rock layers to place events in order.