Correct option is B
Pyrometer:
Pyrometer is the device for measuring relatively high temperatures, such as are encountered in furnaces. Most pyrometers work by measuring radiation from the body whose temperature is to be measured.
Radiation devices have the advantage of not having to touch the material being measured.
Radiation Pyrometers are used to measure the temperature of red-hot metals up to 3000∘ C.
Thermocouple:
A thermocouple is a sensor used to measure temperature. Generally, temperature up to 1400∘ is measured through this device.
It consists of two wire legs made from different metals.
The wire's legs are welded together at one end, creating a junction.
This junction is where the temperature is measured.
When the junction experiences a change in temperature, a voltage is created.
The voltage can then be interpreted using thermocouple reference tables to calculate the temperature.
The upper limit for thermistor devices is around 100∘ C(212∘ F) and RTDs are limited to around 750∘ C(1382∘ F).
