This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Deadliest free radical is - \nSelect and explain. \nA. Hydrogen peroxide(H2O2), B. Superoxide anion (O2 -), C. Hydroxyl ion (OH), D. Peroxynitrite (ONOO)', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Hydroxyl radicals are generally considered to be the most damaging free radicals. They are considered\xa0dangerous because they are extremely reactive.\nFree radicals are chemical species that have a single unpaired electron in the outer orbit. Most of these are\xa0partially reduced reactive oxygen forms that are produced as an unavoidable byproduct of mitochondrial\xa0respiration —> also known as reactive oxygen species.\nThe most important are hydrogen peroxide (H2O2), Superoxide anion (O2-) and hydroxyl radical (OH).\nFree radicals are highly reactive species and toxic -» they can damage the cell membrane and nucleic\xa0acids. Free radicals initiate autocatalytic reactions, whereby molecules with which they react are\xa0themselves converted into free radicals to propagate the chain of damage.\nFree radicals are generated by ionizing radiations, metabolism of exogenous chemicals (CCI4) and even\xa0during normal metabolic (oxidation-reduction) reactions. Nitric Oxide (NO) may also act as free radical.', 'role': 'assistant'}]