Which statements explain the gas exchange that happens at the alveoli? check all that apply.
**multiple answers**

a) carbon dioxide moves from the air in the alveoli to the blood.
b) carbon dioxide moves from the blood to the air in the alveoli.
c) the capillaries that surround the alveoli exchange both carbon dioxide and oxygen.
d) the capillaries that surround the alveoli exchange only oxygen.
e) oxygen is absorbed by the blood in the capillaries that surround the alveoli.
f) oxygen is the air we breathe out when we exhale.

B, C, E

Explanation:

We breathe in oxygen, which travels to the alveoli in our lungs. The alveoli "gives" oxygen to the capillaries, which carry blood. The capillaries "give" its carbon dioxide (which is what oxygen becomes when used by our body) to the alveoli. The carbon dioxide travel back out when we exhale. Although, the air we breathe out has some oxygen content.

The correct answer is: keloids

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