What class of electronic components is capable of using a voltage or current signal to control current flow?

Transistors are electronic components that can control the flow of current using a voltage or current signal. They act as switches or amplifiers in various electronic circuits. When a small control signal is applied to the base of a transistor, it allows a larger current to flow between the collector and emitter terminals. This ability to use a small input signal to regulate a larger output signal is the fundamental principle that makes transistors so valuable in electronics for tasks such as signal amplification, data processing, and switching applications.

In contrast, capacitors store electrical energy but do not control current flow. Inductors store energy in a magnetic field, also lacking the ability to actively control current flow based on a signal. Resistors limit the flow of current but do not serve as a control mechanism that can adjust current based on a signal; they simply provide resistance. Therefore, the correct answer is that transistors are the components designed specifically to use voltage or current signals to control current flow effectively.