Answer:
The lungs of animals excrete carbon dioxide.
Step-by-step explanation:
This is the most logical answer, because others don't have any common point with homeostasis.
Remember that homeostasis refers to all processes that are internally develop in a system in order to maintain the equilibrium, reacting to external stimulation. Which is the case in the first option, carbon dioxide expulsion from animal's lungs is a homeostasis process, because it help to maintain the standard function of the internal systems.