The main nitrogen reservoir in the biosphere is

A. Atmosphere

B. Ocean

C. Organisms

D. Rocks

Answer: Option A

Solution(By Examveda Team)

The main nitrogen reservoir in the biosphere is Atmosphere.
Atmosphere is a layer of gas or layers of gases that envelop a planet and is held in place by the gravity of the planetary body.
It is composed of nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%) and trace gases.