Explanation: To neutralize an acid electrolyte, a basic (alkaline) substance is required. All the listed options are bases and will chemically react with an acid to neutralize it, forming a salt and water. * **A) Ammonium hydroxide** (NH4OH) is a weak base, commonly found in household cleaning solutions. * **B) Baking soda** (sodium bicarbonate, NaHCO3) is a mild base, well-known for safely neutralizing acid spills, including battery acid. * **C) Washing soda** (sodium carbonate, Na2CO3) is a stronger base often used in cleaning products. In amateur radio, this knowledge is crucial for safely managing spills from lead-acid batteries, which contain sulfuric acid electrolyte. Promptly neutralizing battery acid prevents corrosion to equipment and surfaces, and protects against chemical burns. Since all three options are effective bases for neutralizing an acid, "All of the above" is the correct choice.