A 200 V lamp takes a current of 1 A, it produces a total flux of 2,860 lumens :
A 200 V lamp takes a current of 1 A, it produces a total flux of 2,860 lumens. The efficiency of the lamp is
(a) 9.9 lumens/W
(b) 8.9 lumens/W
(c) 10.9 lumens/W
(d) 14.3 lumens/W