exchange gases. break down nutrients. filter wastes and byproducts. carry blood back to the heart.
I gave my students this multiple choice question: The major function of the kidneys is to

Only one answer is correct among these 4 choices:
- exchange gases.
- break down nutrients.
- filter wastes and byproducts.
- carry blood back to the heart.

Could you tell me which one is correct?

filter wastes and byproducts.