Final answer:
The meat loaf that has been left out for 5 hours should be discarded to prevent foodborne illness, as bacteria can multiply rapidly at room temperature within the 'danger zone'.
Step-by-step explanation:
Food Safety and Meat Loaf
According to food safety guidelines, perishable foods left at room temperature for more than two hours should be discarded. This refers to a temperature range between 4 and 60 degrees C (40 and 140 degrees F), known as the 'danger zone', where bacteria can rapidly multiply. The correct option regarding meat loaf that has been left out for 5 hours is b) No, discard the meat loaf. Despite common misconceptions, reheating the meat thoroughly, serving it cold, or conducting a smell test, do not eliminate all potentially harmful bacteria that may have grown during the extended period at room temperature. The safest course of action to prevent foodborne illnesses is to throw away the meat loaf to ensure no one gets sick.