Answer:
D. painting the iron surface
Step-by-step explanation:
Iron gets oxidized in the presence of oxygen and moisture to form iron oxide. This iron oxide is red in color and is known as rust.
Option D is correct. Painting the iron surface is effective in reducing its corrosion. For example when iron is coated with zinc, the zinc is more likely to get oxidized first than the underlying iron.
Option A is incorrect. Increasing the moisture level will facilitate the rusting of iron.
Option B and C are incorrect as rusting is not affected by acids of electrolytes in solutions.