A thermistor is a

A thermistor is a special kind of resistor.
Resistors are electronic components that resist the flow of electricity.
A thermistor is unique because its resistance changes depending on its temperature.
Think of it like this: a normal resistor always has the same resistance, no matter how hot or cold it is.
But a thermistor's resistance goes up or down as its temperature changes.
Option A is incorrect because a thermocouple measures temperature using the difference in voltage between two dissimilar metals.
Option B is incorrect because a thermometer usually measures temperature using the expansion of a liquid or metal.
Option C is the correct answer because a thermistor is basically a small resistor that's very sensitive to heat. Its resistance changes noticeably with temperature changes.
Option D is incorrect because thermistors are not explosive. They are passive components.