Answer:
C. 56.56 VAC
Step-by-step explanation:
The meaning of "average" is unclear in this context.
If the waveform is sinusoidal, or any other symmetrical shape, its average value is zero.
If the waveform is a full-wave rectified sinusoid, its average value is 2/Ï€ times the peak, about 50.93 V.
If you are concerned with the RMS value (not the average), that is 1/√2 times the peak, about 56.57 VAC.