Billions of Years Ago,Earth's Atmosphere Was Composed Primarily of Carbon

Billions of years ago,Earth's atmosphere was composed primarily of carbon dioxide.Where might you go on Earth to find a large fraction of this carbon dioxide today?

A) nowhere, because most of the carbon dioxide has escaped into space
B) anywhere, because most of the carbon dioxide is still in the atmosphere, but nitrogen and oxygen have since been added to it
C) to extinct volcanoes, which are composed of rock from Earth's interior that absorbed the carbon dioxide earlier in Earth's history
D) to mountain ranges such as the Rocky Mountains of North America, which are composed largely of limestone