Explanation: In systems utilizing a sweep display, such as oscilloscopes or radar, precise timing of the horizontal sweep is crucial for a stable image. The synchronizer circuit generates the timing pulses necessary to *initiate* this sweep. It ensures the sweep starts at the correct moment, often locked to an external signal or an internal system trigger, thereby presenting a stable and readable display. The sweep amplifier subsequently amplifies this initiated sweep signal to drive the deflection components. A video amplifier processes image information, not sweep timing. A resolver is typically used for angular position sensing, unrelated to initiating a linear sweep. Therefore, the synchronizer is the circuit responsible for starting the sweep drive.