Answer the following question given this paragraph: 

Life on Earth is carbon-based. Organisms need not only energy but also carbon atoms for building bodies. For nearly all life, the ultimate source of carbon is carbon dioxide (CO 2 ), an inorganic molecule. CO 2 makes up less than 1% of the Earth’s atmosphere.


Q: Life on earth is carbon-based. organisms need not only energy but also carbon ________ for building bodies?

 Choices:

- monoxide

- ions

- crystals

- atoms

A:
atoms
