Like Mars and Venus, Earth Originally Had a Significant Amount

Multiple Choice

Like Mars and Venus, Earth originally had a significant amount of carbon dioxide in its atmosphere.Where is the majority of the carbon now?

A) It has escaped into outer space.
B) It is bound up in the plant life on Earth.
C) It is bound up in rocks.
D) It is dissolved into the oceans.
E) It is still in the atmosphere in the form of complex molecules.