Answer:
A. Compounds contain fixed ratios of different elements.
Explanation:
Water always has this 2:1 ratio of hydrogen to oxygen. Like water, all compounds consist of a fixed ratio of elements. It doesn't matter how much or how little of a compound there is. It always has the same composition.
Proteins are made from Amino acids and, proteins are made by the ribosomes in a cell. <span />
Observation is the answer
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