Final answer:
Cold foods must return to the temperature safety zone at or below 4 degrees C (40 degrees F) within two hours to be safe.
Step-by-step explanation:
Cold foods must return to the temperature safety zone within a specific time frame to ensure they remain safe to consume. The temperature safety zone for refrigerated foods is at or below 4 degrees C (40 degrees F) to inhibit bacterial growth. If perishable foods have been left out and their temperature rises above 4 degrees C (40 degrees F), they should be refrigerated promptly. Foods that have been at a temperature between 4 and 60 degrees C (40 and 140 degrees F) for more than two hours should be discarded, as they may harbor rapidly grown bacteria and thus pose a health risk.