A short linear object of length b lies along the axis of a concave mirror of focal length f at a distanee u from the pole of the mirror. The size of the image is approximately equal to
A. `b((u-f)/(f))^(1//2)`
B. `b((b)/(u-f))^(1//2)`
C. `b((u-f)/(f))`
D. `b((f)/(u-f))^(2)`
