The frequency of the AC source is 50 Hz.

which means the time period of the wave is, 1/50 = 002 sec

Now the average voltage of the wave at the time interval 0.01 sec

If the interval lies between π/2 and 3π/2, the average voltage will be zero. In all the other case it will not be zero.

Hence, it may be zero. Thus B is the correct answer.