What are transistors primarily used for?

Transistors are primarily used as switches and amplifiers in various electronic circuits. As switches, they act as on/off controls for electrical signals, allowing them to manage the flow of current within a circuit. This property makes them essential in digital circuits where binary states (0s and 1s) are needed to operate logic gates and perform computations.

In their role as amplifiers, transistors can increase the power, voltage, or current of a signal while maintaining the same waveform shape. This characteristic is crucial in applications like audio amplification, radio transmission, and telecommunication systems, where weak signals need to be boosted for effective operation.

The other options, while mentioning some functions associated with electronic components, do not capture the primary roles of transistors as effectively as the chosen answer. While switches and rectifiers do play a part in electronic circuits, and amplifiers and filters have their own importance, the specific combination of switches and amplifiers highlights the versatility and fundamental use of transistors in electronic systems. Capacitors and resistors, on the other hand, serve entirely different purposes in circuits, focusing on energy storage and resistance to current flow respectively, rather than the switching and amplification functions attributed to transistors.