Plural. The subject is "concentrations" ("of Vitamin C" just tells you what the concentrations are made of). So It has yet to be explored whether high plasma concentrations of Vitamin C maximize its therapeutic potential.
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Doctor DPlural. The subject is "concentrations" ("of Vitamin C" just tells you what the concentrations are made of). SoIt has yet to be explored whether high plasma concentrations of Vitamin C maximize its therapeutic potential.Thank you very much for your help and clear explanation.