The waveform display on the oscilloscope is shown in the 4 ms/div in horizontal, which represents the figure. The scales of the oscilloscope represent the time and 4 V/div in vertical, which represents the voltage. Referring to the figure, the frequency of the waveform is:
Select one:
a. 60 Hz
b. 125 Hz
c. 50 Hz
d. 250 Hz