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The Respiratory System brings oxygen into the blood; it is the responsibility of the Circulatory System to transport it, with nutrients from digestion, to cells of the body.
The Circulatory System is three-fold: the blood carrying the substances, the vessels in which blood flows, and the heart which pumps it around in a circle-like movement and back (hence the term 'circulatory').
Answer:
I am not so sure but I think it will be B. Nutrition.
Always
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