Answer:
A.) Nitrogen
Explanation:
All carbohydrates, including sugar, therefore contain the same three elements: carbon, hydrogen and oxygen.
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Answer:
While humans, as well as other vertebrates, have a closed blood circulatory system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an open circulatory system containing a heart but limited blood vessels.
Explanation:
The answer is B, unicellular