A step-down chopper, fed from a 120 volt DC source, operates a DC motor whose armature e.m.f. and armature resistance are 100 volt and 0.5Ω respectively. With the magnitude control ratio 0.6, the quadrant of operation DC motor is

(a) First (b) Second (c) Third (d) Fourth

(a) First (b) Second (c) Third (d) Fourth