Imagine you are designing a basic audio amplifier using an operational amplifier (op-amp). You need to know how the internal components, specifically the transistors, contribute to the amplification of the audio signal. Which of the following statements best describes the role of the transistors in the op-amp in this context?

In an op‑amp, the transistors form a differential pair that senses the tiny voltage difference at the inputs and turns it into a larger current difference. This current is then amplified by cascaded transistor stages that provide the high voltage gain needed for an audio amplifier. The transistors act as voltage‑controlled current sources, so a small input voltage produces a proportional change in current that drives the output stage. As a result, the op‑amp can take a millivolt audio signal and boost it to a full‑scale output voltage, much like a small microphone signal is turned into a loudspeaker drive. For example, a 1 mV input difference can cause a transistor current change of several milliamps, producing a much larger voltage swing at the output.