Explanation: A single-phase full-wave rectifier converts both the positive and negative half-cycles of an AC input into a pulsating DC output. For every one complete cycle of the AC input waveform, the full-wave rectifier produces two distinct pulses in the same direction at its output. Because both half-cycles of the input are utilized and effectively inverted or passed to the output as positive pulses, the frequency of the ripple (pulsations) in the output is twice the frequency of the input AC. Therefore, the ratio of the output ripple frequency to the input frequency is 2 to 1. * **A) 1 to 1:** This would be the ratio for a half-wave rectifier's output ripple frequency. * **C) 1 to 2:** This would imply the output frequency is half the input, which is incorrect for a rectifier.