Which statement identifies a chemical sterilization method that uses a gaseous sterilant?

• A. Ethylene oxide
• B. Hydrogen peroxide plasma
• C. Autoclave
• D. Dry heat

Answer: (A)

Gaseous chemical sterilization relies on a chemical agent that is used in the gas phase to inactivate microorganisms. Ethylene oxide fits this scenario perfectly: it is a potent chemical sterilant that exists as a gas at room temperature, allowing it to penetrate packaging and complex interior spaces of heat‑sensitive instruments. It sterilizes by alkylating proteins and nucleic acids, enabling effective sterilization at relatively low temperatures. That makes it the best match for identifying a gaseous chemical sterilant. The other methods rely on heat or non-gas processes—autoclave and dry heat use steam or hot air, and hydrogen peroxide plasma uses vaporized hydrogen peroxide plus plasma, which is a different low‑temperature, gas‑based approach but not the classic gaseous chemical sterilant example.