That's all, I hope that helps...
Eto lang alam ko eh.
15. pulmonary system/ respiratory system
16. b (not sure)
A.The blood returns to the left atrium of the heart
You know im not sure about my answer
Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. It is often referred to by its formula CO2. It is present in the Earth's atmosphere at a low concentration and acts as a greenhouse gas. In its solid state, it is called dry ice.