Which class of amplifier operates over the full cycle?

A Class A amplifier is biased such that current flows through the active device for the entire 360 degrees of the input waveform. This means it operates over the full cycle of the signal. Because the transistor never turns off, Class A amplifiers offer excellent linearity and very low distortion, making them ideal for high-fidelity audio and sensitive RF receiver stages. However, this continuous conduction means they draw maximum power all the time, resulting in very low electrical efficiency. To distinguish from the distractors: Class B operates for exactly half the cycle (180 degrees), Class AB operates between 180 and 360 degrees, and Class C operates for significantly less than 180 degrees.