Answer:haemoglobin
Explanation:
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.
A chemical reaction is a process by which atoms or groups of atoms in a particular substance are rearranged from the arrangement within the reactants to a new arrangement within the products.
During a controlled experiment, a scientist will isolate and test (D) a single variable. A conclusion, nor a mass of information can be isolated or tested. A control group is the group that would receive a placebo, so testing that would be futile.
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