What Discoveries in the Fossil Record Led to Questioning the Concept

Multiple Choice

What discoveries in the fossil record led to questioning the concept that species didn't change?

A) the oldest layers contain fossils of simpler organisms
B) more recent layers contain fossils more similar to existing species
C) many fossils were found of extinct animals
D) more recent layers contain fossils that are more complex than earlier ones
E) all of these are discoveries in the fossil record that led to questioning the concept that species didn't change