The Atmosphere Contains a Relatively Low Concentration of Carbon, Mostly

Multiple Choice

The atmosphere contains a relatively low concentration of carbon, mostly in the form of CO₂.Why is this small amount considered important in the carbon cycle?

A) Although small, it is the largest pool of carbon on Earth.
B) It is the only source of carbon capable of moving from one pool to another.
C) It remains in the atmosphere for long periods of time.
D) Its concentration in the atmosphere is currently decreasing.
E) It is the source of carbon for living organisms that carry out photosynthesis.