Explanation: The video amplifier in a radar or display system is responsible for processing and amplifying signals that will be presented on the screen. * **Low level video** (A) represents the actual radar return echoes or other visual information. These signals are typically weak and require significant amplification to drive the display device and create a visible image. * **Fixed range rings** (B) are generated timing signals that produce concentric circles on the display, indicating set distances from the radar. These are essential for range measurement and must be fed into the video amplifier to be superimposed on the video signal. * **Variable range rings** (C) are similar to fixed rings but allow the operator to adjust their position, providing a precise measurement tool. Like fixed rings, these signals are also combined and amplified by the video amplifier to be displayed. Therefore, to create a complete and interpretable display, the video amplifier receives and processes all these signals.