Question

What do these layers and their fossils suggest about Earth's history?

ОА.
Lifeforms on Earth have been the same over time.
ОВ.
No lifeforms were present when these layers formed.
OC. Only one kind of lifeform lived where these layers formed.
OD
There have been changes in Earth's lifeforms over time.

Answer 1

This is the answer: There have been changes in Earth's life forms over time.