I believe it's the last two. "makes the lungs able to fill more completely" and "helps the blood vessels dilate more easily" hope this helps, have an amazing day :)
Answer:
Metabolic wastes or excretements are substances left over from metabolic processes (such as cellular respiration) which cannot be used by the organism (they are surplus or toxic), and must therefore be excreted.
This is what i found out i hope this is a good enough answer!! :P
