What term describes the most basic semiconductor component used to amplify?

A transistor is the fundamental active semiconductor component used in modern electronics to amplify and switch electrical signals. By applying a small input current or voltage, it can proportionally control a much larger output current. The other choices represent semiconductor devices that cannot amplify. A diode, which is essentially a basic P-N junction, only allows current to flow in one direction and is used for rectification. A varactor is a specialized diode used as a voltage-controlled capacitor in tuning circuits, not for signal amplification.