Final answer:
Foods must be cooled from 60 degrees C to 20 degrees C within 2 hours to prevent bacterial growth and ensure food safety.
Step-by-step explanation:
The question relates to the proper cooling times for food to ensure safety from bacterial growth. Foods must be cooled from 60 degrees C (140 degrees F) to 20 degrees C (68 degrees F) within a certain time frame to prevent the rapid multiplication of microorganisms.
According to food safety guidelines, perishable foods left at a temperature between 4 degrees C (40 degrees F) and 60 degrees C (140 degrees F) for more than two hours should be discarded. Therefore, the correct answer is (c) 2 hours.