Correct option is D
Thermocouple and solar cell are both active transducers:
Thermocouple: An electrical device that produces a voltage based on temperature, which can be used to measure temperature. Thermocouples are used in many applications, including thermometers, thermostats, and flame sensors.
Solar cell: An electronic device that converts light energy into electricity. Solar cells can also be used to detect light or measure light intensity. Solar cells are often used as the building blocks of photovoltaic modules, also known as solar panels.
