A 5-yr-old child ingests 50 iron tablets, each with 27 mg of iron. -Within 6 hrs ,he develops abdominal pain and lethargy. -Examination shows ,he is hypotensive. -laboratory studies shows metabolic acidosis. Through formation of which of the following components is the cell injury in this child most likely mediated? 1. Ascorbic acid 2. Nitric oxide 3. Hydroxyl radical 4. Hemosiderin 5. Superoxide dismutase