Explanation: A video amplifier is designed to amplify the signal that determines the brightness or intensity of a display (e.g., a CRT screen in a radar or television). * **A) Resolver:** A resolver is an electromechanical device used to measure or control angular position. It generates sine and cosine voltages proportional to an angle. These signals are used in control systems and navigation, not as inputs to modulate the intensity of a display, and therefore, not usually an input to a video amplifier. * **B) Range:** In the context of radar displays, "range" often refers to the specific distance being observed or displayed. A range-gate signal, for instance, might be used to enable or disable the video amplifier's output, effectively selecting which range of echoes are shown. So, signals related to range *can* be inputs that control the video amplifier's operation. * **C) Brilliance (Brightness):** This control adjusts the overall average intensity of the display. It typically sets the DC bias level of the video amplifier, affecting the baseline brightness. * **D) Contrast:** This control adjusts the difference between the brightest and darkest parts of the image, which is achieved by varying the gain of the video amplifier. Given these definitions, a resolver's function is entirely separate from video signal processing, making it the signal least likely to be an input to a video amplifier.