which of the following gases does an animal need to survive?
oxygen blood carbon monoxide food glycogen helium H20 warm
A B C D E F G H
Air is mostly nitrogen and oxygen.
an animal requires oxygen and nitrogen for survival. 
which of the following gases does an animal need to survive? (A) oxygen (B) blood (C) carbon monoxide (D) food (E) glycogen (F) helium (G) H20 (H) warm