Question

a scientist discovers a fossil of an unknown, extinct sea creature deep within the earth’s oldest rock layers. what is the most logical conclusion the scientist can draw from this discovery?
life on earth has changed over a very long period, as shown by ancient, extinct species.
the earth’s geological features must have formed very rapidly.
this creature must have been one of the last species to evolve.
this discovery proves that all modern animals evolved from this one creature.

Explanation:

The discovery of a fossil in old rock layers relates to the evolution of life over time. The first option ("Life on Earth has changed over a very long period, as shown by ancient, extinct species") logically connects the fossil (ancient, extinct species) to the idea that life evolved over a long time. The other options make unfounded claims (e.g., rapid geological feature formation, being the last species, or proving all modern animals evolved from it) which are not supported by a single fossil discovery.

Answer:

The top blue box (the first option: "Life on Earth has changed over a very long period, as shown by ancient, extinct species")