Construct the best short explanation for a patient of how dissolved minerals (electrolytes) enable nerves to send messages to muscles.

• A. Only vitamins generate electrical signals in nerves; minerals simply change the pH of the blood which indirectly makes nerves more or less sensitive in a way unrelated to ion movement.
• B. Minerals form large, insoluble crystals in the bloodstream that physically push on nerves causing them to fire, and muscles react to this mechanical pressure without any change in electrical properties.
• C. Electrolytes are digested into amino acids that then enter nerve cells to directly supply the energy required for muscle contraction, so the role of ions is purely nutritive rather than electrical.
• D. When minerals like sodium and potassium dissolve in body fluids they become charged ions; nerve cells open channels to move these ions across their membranes, creating rapid voltage changes (electrical signals) that travel down nerves to tell muscles to contract.

Answer: (D)