How should used oil be managed to minimize environmental risk?

• A. Stored together with hazardous waste in the same area.
• B. Mailed to a recycling facility for all waste.
• C. Buried on-site.
• D. Stored separately from hazardous waste, labeled as used oil, kept in good condition to avoid leaks, and sent for recycling or proper disposal.

Answer: (D)

The main idea is to prevent environmental contamination by handling used oil in a controlled, identifiable way and ensuring it goes to proper recycling or disposal. Used oil can contain contaminants that threaten soil and groundwater, so it must be kept separate from other wastes to avoid cross‑contamination, clearly labeled so everyone knows what it is, and maintained in good condition to prevent leaks or spills. Then it should be sent to an authorized facility for recycling or proper disposal.

Storing used oil with hazardous waste mixes potentially harmful substances, increasing risk and regulatory problems. Mailing all waste to a recycling facility isn’t a reliable or universally appropriate method and ignores proper handling and shipping rules. Buried on-site creates an immediate and ongoing environmental hazard.