Which brief statement correctly contrasts manganese and magnesium based on the lesson?

• A. Magnesium has no enzymatic roles and functions only as an inert structural mineral, while manganese regulates blood pH directly and is required in gram amounts daily.
• B. Manganese and magnesium are chemically identical in biological systems, and therefore interchangeable in dietary recommendations and toxicity profiles across all populations.
• C. Manganese is a vitamin and needs to be synthesized by gut bacteria, while magnesium is exclusively obtained from animal products and has no role in metabolism.
• D. Both manganese and magnesium act as enzyme cofactors in metabolism; magnesium is a major mineral and electrolyte whereas manganese is a trace mineral (RDA ~1.8–2.3 mg) and toxic only at very high doses or in industrial exposures.

Answer: (D)