Explanation: Storage cells, particularly lead-acid batteries commonly used in amateur radio, rely on a precise chemical balance within their electrolyte. Adding water is sometimes necessary to replenish evaporated H2O, but it must be free of contaminants. **A) It should be chemically pure or distilled:** This is correct because impurities found in tap water (minerals, chlorine, etc.) or sea water (salts) can interfere with the battery's chemical reactions. These contaminants can lead to sulfation, corrosion of the plates, increased self-discharge, reduced capacity, and a significantly shortened battery lifespan. Distilled or deionized water ensures only H2O is added, maintaining the integrity of the electrolyte. **B) It should be only sea water:** This is incorrect. Sea water contains high concentrations of salts and minerals that would severely contaminate the electrolyte, rendering the battery unusable and potentially damaging it beyond repair. **C) Tap water is as good as any:** This is incorrect. Tap water contains dissolved minerals and chemicals (like chlorine) that are detrimental to battery chemistry, causing the same issues mentioned above, albeit typically slower than sea water.