Which pairing correctly identifies a waveform category and an example modality for that category?

• A. Monophasic (HVPC) — HVPC
• B. Monophasic (TENS) — HVPC
• C. Biphasic asymmetrical (NMES) — NMES
• D. Polyphasic — TENS outputs

Answer: (A)

Waveform category tells you the shape and direction of the current pulses. Monophasic means the current flows in one direction with each pulse. High-voltage pulsed current devices are built to deliver short, high-voltage, unidirectional pulses, so HVPC is exactly a monophasic waveform. That makes the pairing of monophasic with HVPC correct, since HVPC is the modality that uses that kind of pulse pattern.

The other options mix typical waveform patterns with modalities in ways that don’t align with how those devices usually operate. TENS units are commonly biphasic (and sometimes polyphasic) rather than monophasic; NMES typically uses biphasic pulses (often symmetric rather than asymmetrical); and polyphasic descriptions aren’t the standard way TENS outputs are characterized. So the pairing that best matches a waveform category to a real-world modality is the monophasic category with HVPC.