Which of the Following Is a Plausible Explanation for the Presence

Multiple Choice

Which of the following is a plausible explanation for the presence of carbon dioxide in Earth's early atmosphere?

A) Volcanic eruptions could have released carbon dioxide into the atmosphere.
B) Cyanbacteria were present on Earth 3.5 billion years ago.
C) Retroviruses catalyzed the formation of carbon dioxide.
D) Geysers may have produced the Earth's early environment.
E) Chemical reactions with water resulted in the formation of carbon dioxide.