Information on government websites is usually impartial, so A is eliminated. Additionally, information on a government website is not necessarily easy to understand, so that choice cannot be the correct answer either. The only remaining choice is B, so it is correct.
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
