What type of resistor changes its resistance based on temperature?

The correct answer is C, thermistor, because a thermistor is a type of resistor whose resistance varies significantly with temperature. Unlike fixed resistors, which maintain a constant resistance regardless of temperature changes, thermistors are designed to exploit this temperature dependence for various applications, such as temperature sensing and control systems.

Thermistors are typically made from semiconductor materials and can be classified into two types: NTC (Negative Temperature Coefficient) thermistors, where resistance decreases as temperature increases, and PTC (Positive Temperature Coefficient) thermistors, where resistance increases with temperature. This unique characteristic allows thermistors to be used in circuits where temperature monitoring and response are critical.

Other options like variable resistors and fixed resistors do not change their resistance significantly with temperature, and capacitors are not resistors; they serve a different function in circuits by storing electrical energy.