Answer the following question given this paragraph: 

User:helix84/Wikimedia Commons. Gas exchange is the movement of oxygen into the blood and carbon dioxide out of the blood . CC BY 2.5.


Q: What gases move in and out of blood during gas exchange?

 Choices:

- oxygen, carbon monoxide

- nitrogen, carbon dioxide

- oxygen, nitrogen

- oxygen, carbon dioxide

A:
oxygen, carbon dioxide
