Final answer:
Leftover TCS food should be discarded if left in a cooler for over 24 hours to prevent the growth of harmful bacteria that can thrive between temperatures of 40 and 140 degrees F if left for more than two hours.
Step-by-step explanation:
The correct answer to the student's question is that leftover Time/Temperature Control for Safety (TCS) food should be thrown out if it has been in a cooler for more than 24 hours. TCS food requires strict temperature control to prevent the growth of pathogenic microorganisms and the production of toxins. Foods that are left at temperatures between 4 and 60 degrees C (40 and 140 degrees F) for more than two hours can see rapid bacteria growth, which can render them unsafe to consume, even if subsequently heated thoroughly. It is critical to cool down perishable foods as soon as possible and keep them properly refrigerated to ensure safety.