How Is Atmospheric Nitrogen Converted to a Usable Form in the Biosphere

Multiple Choice

How is atmospheric nitrogen converted to a usable form in the biosphere?

A) Atmospheric nitrogen is directly available to plants and animals through the photosynthetic process and trophic relationships.
B) It is absorbed into plants via stoma and converted within the plant to a usable form.
C) Bacteria within root nodules of legumes chemically change the atmospheric nitrogen into nitrates and ammonia.
D) Atmospheric nitrogen is completely unavailable to plants and animals and,as a result,synthetic fertilizers must be used.
E) Atmospheric nitrogen combines with atmospheric moisture and a free oxygen molecule to form nitric acids (HNO3) ,which enters in the biosphere as mildly acidic precipitation.