Why Does Earth Have So Little Carbon Dioxide in Its

Why does Earth have so little carbon dioxide in its atmosphere compared to Venus?

A) Earth has just as much carbon dioxide as Venus,but most of it is locked up in carbonate rocks rather than being free in the atmosphere.
B) Earth's volcanoes outgassed far less carbon dioxide than those on Venus.
C) Earth once had a lot of carbon dioxide,but it was lost to space during the heavy bombardment early in our solar system's history.
D) Chemical reactions turned Earth's carbon dioxide into nitrogen.