Explanation: A Class A amplifier is biased such that it conducts current for the entire 360 degrees of the input signal cycle. This continuous conduction ensures that the output signal is a faithful, linear reproduction of the input, minimizing distortion. While this results in lower efficiency compared to other classes, it's ideal for applications requiring high fidelity, such as linear RF amplifiers and audio pre-amplifiers, where signal integrity is paramount. Options A, C, and D describe other amplifier classes: * **A) Less than 180 degrees:** Characteristic of Class C amplifiers, which are highly efficient but produce significant distortion, making them suitable only for amplifying constant-amplitude RF signals (e.g., CW, FM). * **C) More than 180 degrees but less than 360 degrees:** This describes Class AB, a compromise between Class A's linearity and Class B's efficiency. * **D) Exactly 180 degrees:** This is the defining characteristic of a Class B amplifier, which conducts for half of the input cycle.