Final answer:
Using a thermometer is the only acceptable method for accurately checking food temperature, ensuring it is safe to eat by reaching temperatures that kill harmful bacteria.
Step-by-step explanation:
The only acceptable method for checking the temperature of food is by using a thermometer. This is essential because visual appearance and touch are not accurate indicators of whether food has reached a high enough temperature to kill bacteria. Thermometers measure temperature by using materials that change size (expand or contract) in response to heat or coolness. Traditional thermometers, such as mercury or alcohol types, have a liquid reservoir that moves up or down a scale as the temperature changes. More advanced thermometers, such as infrared thermometers (pyrometers), measure temperature through radiation emitted by the object—no physical contact is necessary.