Nitrogen Is the Most Abundant Element in the Atmosphere, and a Crucial

Nitrogen is the most abundant element in the atmosphere, and a crucial component of proteins, vitamins, and nucleic acids. However, plants and other producers cannot use nitrogen in its natural form (N2) . Nitrogen has to undergo a process called nitrogen fixation. What does this process involve?

A) Ammonia is converted to nitrate.
B) It is the synthesis of ammonia from nitrogen gas by certain bacteria.
C) Nitrate is converted to ammonia.
D) Nitrogen is accumulated in dead organic matter.
E) It is undertaken by denitrifying bacteria.