What must you insert into the thickest part of the food item to measure its temperature accurately?

To measure the temperature of food accurately, the instrument used should be inserted into the thickest part of the food item. This is essential because the thickest area is where the temperature is typically the lowest, especially with large cuts of meat or dense dishes.

The correct choice aligns with the description of a "stem" thermometer, which has a metal stem designed specifically for penetrating foods to provide an accurate reading. By placing the thermometer's stem in the thickest part, you ensure the temperature measurement reflects the center of the food, which is crucial for food safety.

Other options like a probe or a sensor can also be types of thermometers, but the term "stem" highlights the specific part of the thermometer that directly engages with the food to provide a reliable reading. A dial thermometer typically features a dial for reading temperatures, but without the context of “thickest part,” the term may not convey the same specificity regarding where to place it for accuracy.