Which trigger mode is most effective when using an oscilloscope to measure a linear power supply’s output ripple?

A linear power supply derives its DC output directly from the AC mains (the 'line'), meaning any ripple present on the output will be a direct multiple of the local AC line frequency (e.g., 60 Hz or 120 Hz). Setting the oscilloscope's trigger mode to 'Line' synchronizes the sweep directly to the AC mains frequency. This provides a stable, stationary display of the ripple waveform, making it much easier to measure its amplitude and characteristics. Other trigger modes like Edge or Level would struggle to maintain a perfectly stable lock on the small, sometimes noisy ripple voltage riding on top of a large DC offset.