Concept:Pure water without dissolved salts contains very few ions, so it cannot conduct electricity well.
Explanation:Distilled water is purified by boiling and condensing, which removes dissolved minerals and salts.
Without these ionic impurities, it has no free ions to carry electric current.
Tap water, sea water, and drinking water contain dissolved salts, making them better conductors.
Therefore, distilled water is the poorest conductor of electricity among the options.
Answer:A. Distilled water