Question

what can fossils found in rock layers tell scientists?
the size of earth
which living things existed and when they lived
how old the oceans are
the location of volcanoes

Explanation:

Fossils are the remains or traces of ancient organisms. Rock layers (strata) often contain fossils. By studying the fossils in different rock layers, scientists can determine which living things existed (as the fossils are of those organisms) and when they lived (since different rock layers correspond to different geological time periods). The size of the Earth is determined through methods like measuring the Earth's circumference (not by fossils in rock layers). The age of the oceans is calculated using techniques like radiometric dating of ocean - floor rocks and not directly from fossils. The location of volcanoes is determined by tectonic plate boundaries and volcanic activity patterns, not by fossils in rock layers.

Answer:

Which living things existed and when they lived