A sinusoidal voltage of peak value `200` volts is connected to a diode and resistor `R` in the circuit shown so that half wave rectification occurs. If the forward resistance of the diode is negligible compared to `R` the `rms` voltage (in volt) across `R` is approximately
A. 200
B. 100
C. `(200)/(sqrt(2))`
D. `280`