Final answer:
Previously cooked and refrigerated foods must be rapidly reheated to 165°F (74°C) using a stove before being placed in a hot holding unit.
Step-by-step explanation:
The correct answer to the student's question is a) 165°F (74°C) using a stove. According to safe food-handling practices, previously cooked and refrigerated foods that will be served from a hot holding unit must be rapidly reheated to 165°F (74°C) for at least 15 seconds before it can be placed in the hot holding unit. This rapid reheating process should be done using a direct heat source like a stove, as it ensures that any potentially harmful bacteria are destroyed, making the food safe to eat. Using a microwave, hot plate, or broiler may not consistently achieve the temperature necessary to prevent bacterial growth which could lead to foodborne illness.