The correct answer is D: RMS is measured for both sinusoidal and non-sinusoidal signals. The benefit of making voltage measurements with a true-RMS calculating meter is that RMS is measured for both sinusoidal and non-sinusoidal signals. True-RMS meters accurately measure the RMS value regardless of waveform shape. Ordinary AC voltmeters are calibrated for sine waves and give incorrect readings for non-sinusoidal waveforms (like square waves, triangle waves, or distorted signals). True-RMS meters actually calculate the root-mean-square value of the waveform, so they give accurate readings for any waveform shape. This is important when measuring complex signals, distorted waveforms, or signals with harmonics. True-RMS meters are essential for accurate measurements of non-sinusoidal signals common in digital circuits and power electronics.