Aldrin is an organochlorine insecticide that was widely used until the 1970s, when it was banned in most countries. It is a colourless solid. Before the ban, it was heavily used as a pesticide to treat seed and soil. It is a chlorinated hydrocarbon. Thus, option C is correct. A carbamate is an organic compound derived from carbamic acid (NH2COOH). Thus, option D is wrong. Malathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity. It is not a chlorinated hydrocarbon. Thus, option A is wrong. Pyrethrum was a genus of several Old World plants now classified as Chrysanthemum or Tanacetum which are cultivated as ornamentals for their showy flower heads. Thus, option B is wrong.