Which of the following are true statements about cycles of some of the Earth's major components?

Question

A. Atmospheric nitrogen is abundant, but not very useful to life. Before it can be used it must be"fixed" and converted to a secondary form.
B. The cycling of carbon, nitrogen, and oxygen involves members of the plant kingdom.
C. Oxygen generally cycles through three different states - solid liquid and gas.
D. Oxygen and water vapor are the two most abundant gases in the atmosphere.
E. Salt water and fresh water move through separate water cycles.

Answer 1

I'll go for A and B only

Answer 2

I agree with the other posters: A and B only.

Answer 3

A and B are true.