Which of the following is NOT a type of capacitor?

The correct answer is Tri-polarized, as it is not recognized as a standard type of capacitor in electrical engineering or electronics. Capacitors are classified based on their construction, polarization, and application.

Non-polarized capacitors are widely used in various applications and can be connected in either direction, making them versatile for AC circuits. Electrolytic capacitors are polarized, meaning they must be connected in a specific direction, and are typically used in applications requiring larger capacitance values, such as power supply filtering. Variable capacitors allow for a change in capacitance and are commonly found in tuning circuits, such as radios.

In contrast, the term "tri-polarized" does not exist in the context of capacitor types, highlighting that it is not a valid choice among the standard classifications of capacitors.