The Difference in the Fundamental Niche and the Realized Niche

The difference in the fundamental niche and the realized niche is

A) the fundamental niche is the actual niche that a species occupies while the realized niche is the potential area that the species is capable of inhabiting.
B) the fundamental niche is the entire niche that a species is capable of using while the realized niche is just what is being occupied.
C) the fundamental niche is smaller than the realized niche.
D) the realized niche is theoretical while the fundamental niche is the entire niche that an organism can use.