Question

How is modern Earth different from Earth over four billion years ago?

Constantly bombarded with comets and asteroids
Little to no oxygen
High levels of ultraviolet radiation
Protective atmosphere

Answer 1

its either C or D

Step-by-step explanation:

Answer 2

Answer: D, protective atmosphere

Step-by-step explanation:

Modern Earth has a protective atmosphere while Earth over four billion years ago did not have one. Modern Earth is not constantly bombarded with comets and asteroids, but Earth over four billion years ago was.