Well you do not have a set of choices but here is an example!
Sweating, your body releases water to cool down the skin of your body!
When blood is in the lungs,
where oxygen is plentiful, oxygen easily binds to the first subunit and then quickly fills up the remaining ones. Then, as blood circulates through the body, the oxygen level drops while that of carbon dioxide increases. In this environment, hemoglobin releases its bound oxygen.
