Which type of electronic component is characterized by emitter, collector, and base terminals?

The correct choice identifies an NPN transistor, which is characterized by its three fundamental terminals: the emitter, collector, and base.

In an NPN transistor, the emitter terminal is connected to a negative supply, the collector to a positive supply, and the base is the control terminal that modulates the flow of electrons between the emitter and the collector. When a small current flows into the base, it allows a larger current to flow from the collector to the emitter, effectively functioning as a switch or amplifier in various electronic applications.

In contrast, the other electronic components listed do not have these three terminals. A capacitor consists of two plates separated by an insulating material and is used to store energy. A diode has two terminals, anode and cathode, which allow current to flow in one direction only. A resistor is a two-terminal component that provides resistance to the flow of current. None of these other components can be characterized by the emitter, collector, and base setup found in transistors, highlighting the unique structure and function of NPN transistors in electronic circuits.