A point source of light B is placed at a distance L in front of the centre of a mirror of width d hung vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror at a distance 2L from it. The distance over which he can see the image of the light source in the mirror is

d/2 d 2d 3d

3d

In similar ΔABI & ΔMNI MN/AB = IQ/IP ⇒ MN = (3L/L)(d) = 3d Hence (D) is correct