Fact 1: An animal requires air for survival.  Fact 2: Mammals are animals with lungs, and they breath air.  Given the two facts above, how do animals lungs help them survive?

Choices:
(i) they body they live in.
(ii) compound of hydrogen oxygen.
(iii) They help them drink water.
(iv) it keeps an organism warm.
(v) They help them sleep.
(vi) prevents the transfer of heat.
(vii) They help them breathe.
(viii) They help them eat.
Answer:
(vii)