Detailed Explanation:

Galvanized iron is coated with zinc, which reacts with oil components to form toxic zinc compounds that make the oil unsafe for consumption.

The chemical reaction also causes rancidity, degrading the oil's taste, smell, and nutritional quality.

Moisture and acidic impurities in oil corrode the zinc coating, exposing the underlying iron to rust formation.

Since all three effects—toxicity, quality degradation, and corrosion—occur simultaneously, the correct answer is All of above.