Explanation: In a display system power supply, which commonly utilizes a Switch-Mode Power Supply (SMPS) design, a chopper acts as a crucial electronic switch. After the AC input is rectified and filtered into a raw DC voltage, the chopper rapidly switches this DC on and off at a high frequency. This pulsed DC is then fed to an inverter stage. By precisely controlling the duty cycle (the ratio of ON time to total period) of this high-speed switching, the chopper effectively regulates the average DC voltage supplied to the inverter. This action is fundamental to the efficient conversion and regulation of power in an SMPS. Option B is incorrect because choppers are DC-to-DC converters and do not directly interrupt the AC supply line. Option C is generally incorrect; while a chopper regulates DC, it often pre-regulates an intermediate voltage, with the final precise 5V regulation usually handled by later stages after the high-frequency transformer. Option D is incorrect as choppers operate on DC, not the AC input.