Why does impedance matter for a fast signal but not a slow one?

Select one answer.

• Because a fast signal draws far more current than a slow one does and therefore heats up the copper of the trace very much more strongly than a slow signal ever could.
• Because a slow signal is always carried on a much wider trace than a fast one is.
• A fast signal travels as a wave along the trace as a transmission line, and an impedance change reflects part of it, distorting the waveform.
• Because fast signals cannot pass through copper at all without a special coating.