I believe the answer is A
Answer:
Inside the air sacs, oxygen moves across paper-thin walls to tiny blood vessels called capillaries and into your blood. A protein called haemoglobin in the red blood cells then carries the oxygen around your body.
Explanation:
Hope this helps
Answer:
I think its bone, air and hence
Explanation:
I'd say to help the reader quickly locate geographic regions.
A compound that has Carbon and Hydrogen
