A converging lens forms a three times magnified image of an object, which can be take on a screen. If the focal length of the lens is 30 cm, then the distance of the object from the lens is
(a) - 55 cm
(b) - 50 cm
(c) - 45 cm
(d) - 40 cm
(a) - 55 cm
(b) - 50 cm
(c) - 45 cm
(d) - 40 cm