Which choice best describes a differential amplifier?

The choice that best describes a differential amplifier is one that measures the difference between two inputs and amplifies that difference. This characteristic is fundamental to the operation of a differential amplifier, which takes two input signals and outputs a single signal that corresponds to the voltage difference between those inputs. This ability to reject common-mode signals—signals that are present equally on both inputs—makes differential amplifiers particularly useful in applications where noise and interference might affect both inputs equally, such as in biomedical instrumentation and other sensitive measurement systems.

Differential amplifiers are essential in many applications because they enhance the desired signal (the difference) while minimizing any unwanted noise or interference that may affect both input channels. This feature is critical in achieving high accuracy in signal processing, making this description very relevant.