I agree that b would be the answer
The circulatory system will make the heart pump faster, moving blood, oxygen, and nutrients around the body. the excretory system will excrete waste like sweat through the skin, maintaining a steady body temp.
Monomers are the building blocks of the four basic macromolecules of life- monosaccharides are the monomers of carbohydrates, amino acids are the monomers of proteins, glycerol/fatty acids are the monomers of lipids, and nucleotides are the monomers of DNA.
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