Answer:
B. Synthesizing a complex molecule
Step-by-step explanation:
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In this case, since catabolic reactions are related to the synthesis of complex biomolecules and metabolic reactions to the breaking down of complex molecules to obtain energy from (say start), we infer that the appropriate answer is:
B. Synthesizing a complex molecule
Because regardless C. also mentions the synthesis of a compound, carbonic acid is not a complex one in comparison to the biomolecules we produce during our cellular cycles.
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