Which one of the following instruments can be used to measure -250℃ temperature ?

To measure a temperature as low as -250°C, liquid-in-glass thermometers are unsuitable because their filling materials freeze at much higher temperatures. Mercury thermometers have a freezing point of approximately -38.8°C to -39°C. Alcohol-based thermometers, while better for cold environments, typically only reach down to -112°C or -115°C. Clinical thermometers are even more restricted, generally measuring only between 35°C and 42°C for human body temperature. In contrast, thermocouple-based thermometers utilize the Seebeck effect, where a voltage is generated between two different metal conductors proportional to the temperature difference. Specific types of thermocouples and Resistance Temperature Detectors (RTDs) are capable of measuring cryogenic temperatures down to -200°C and even lower in specialized industrial or scientific configurations. Therefore, a thermocouple-based instrument is the only viable option among the choices for measuring -250°C.