A single-phase half-controlled rectifier is driving a separately excited dc motor. The dc motor has a back emf constant of 0.5 V/rpm. The armature current is 5 A without any ripple. The armature resistance is 2 Ohm. The converter is working from a 230 V, single-phase ac source with a firing angle of 30o . Under this operating condition, the speed of the motor will be
(A) 339 rpm (B) 359 rpm (C) 366 rpm (D) 386 rpm