Which class of amplifier has the poorest linearity and the most distortion?

Linearity in an amplifier refers to how accurately the output signal's amplitude mirrors the input signal. Because a Class C amplifier is biased well beyond cutoff, it only amplifies a small portion of the input waveform's peaks, conducting for less than half (180 degrees) of the cycle. This severe clipping action destroys the original shape of the amplitude envelope, resulting in extremely poor linearity and generating a massive amount of harmonic distortion. While this high distortion makes Class C entirely unsuitable for amplitude-modulated modes like AM and SSB, a properly designed tuned tank circuit on the output effectively filters out the harmonics, allowing the amplifier to be used efficiently for FM or CW signals.