Which of the Following Statements Most Accurately Describes a Difference

Which of the following statements most accurately describes a difference between the current atmosphere and that of early Earth?

A) Compared to today, early Earth had an atmosphere richer in gases released from volcanic eruptions.
B) Compared to today, early Earth had a less oxidizing atmosphere.
C) Compared to today, early Earth experienced less high-energy radiation from the sun.
D) Compared to today, early Earth had an atmosphere with greater quantities of ozone.