The Early Martian Atmosphere Probably Contained as Much Nitrogen as Earth's

Multiple Choice

The early Martian atmosphere probably contained as much nitrogen as Earth's atmosphere. But the present Martian atmosphere is less than 5% nitrogen gas. Where did the original nitrogen gas go?

A) It was locked up in the rocks and minerals of the Martian surface.
B) At the elevated temperatures of the early Martian atmosphere, nitrogen's average velocity was high enough to cause it to escape.
C) As UV-absorbing H₂O and CO₂ were depleted, UV radiation penetrated the Martian atmosphere. This was absorbed by N₂, which received enough energy to escape.
D) It is still present in nitric acid droplets and vapors in the Martian clouds.