If the a.c. input to a half-wave rectifier is an r.m.s value of 400/√2 volts, then diode PIV rating is__________________?

If the a.c. input to a half-wave rectifier is an r.m.s value of 400/√2 volts, then diode PIV rating is__________________?

A. 400/√2 V
B. 400 V
C. 400 x √2 V
D. none of the above