The correct answer is D) Poisonous phosgene gas. Ethyl chloride is a flammable gas that, when ignited, will produce poisonous phosgene gas. Phosgene is an extremely toxic chemical that was used as a chemical weapon in World War I. When ethyl chloride burns, the chlorine atoms in the molecule can react with oxygen to form phosgene (carbonyl chloride), which is a highly dangerous compound. The other answer choices are incorrect because they do not accurately describe the byproducts of burning ethyl chloride. A) and C) refer to other chemical reactions not related to ethyl chloride, while B) describes a different chlorine-containing gas rather than the specific phosgene that is produced.