In a differential amplifier, signals common to both inputs are:

In a differential amplifier, signals that are common to both inputs are effectively cancelled out. This is due to the nature of how a differential amplifier works; it amplifies the difference between the two input signals while rejecting any signal that is identical in both inputs, which is known as common-mode signal.

When both inputs receive the same signal, the amplifier subtracts one input from the other, leading to a net output of zero for that common signal. This characteristic allows the differential amplifier to enhance the signals of interest (those that are different between the inputs) while minimizing the effects of noise or interference that affects both inputs equally.

Other options, such as amplification or specific percentages of attenuation, do not accurately describe the behavior of a differential amplifier regarding common-mode signals. The emphasis on cancellation highlights the amplifier's design purpose, which is to isolate and amplify the differential signal while nullifying the common signals.