A body is located on a wall. Its image of equal size is to be obtained on a parallel wall with the help of a convex leng. The lens is placed at a distance d ahead of second wall, then the required focal length will be:
A. `only(d)/4`
B. `only(d)/(2)`
C. more than `(d)/(4)` but less than `(d)/(2)`
D. "less then"`(d)/(4)`
