A bulb is located on a wall. Its image is to be obtained on a parallel wall with the help of convex lens. If the distance between parallel walls is 'd' then required focal length of lens placed in between the walls is :-
A) Only \[\frac{d}{4}\]
B) \[\frac{d}{2}\]
C) More than \[\frac{d}{4}\] but less than \[\frac{d}{2}\]