For which of the following modes is a Class C power stage appropriate for amplifying a modulated signal?

Class C amplifiers are highly efficient, but they are also extremely non-linear. Because their active device conducts for less than half of the input cycle, they severely distort the amplitude of the signal passing through them. However, Frequency Modulation (FM) and Continuous Wave (CW) signals do not rely on amplitude variations to carry information; their data is encoded entirely in their frequency or timing. Therefore, an FM signal can be passed through a non-linear Class C amplifier without losing any modulation information. In contrast, Single Sideband (SSB) and Amplitude Modulation (AM) require linear amplifiers (like Class A or AB) to preserve the delicate amplitude variations that carry the audio signal. Using a Class C amplifier on an AM or SSB signal would result in unintelligible audio.