Solve question 7

7.  If an object is placed at A (OA > f); Where f is the focal length of the lens the image is found to be formed at B. A perpendicular is erected at O and C is chosen on it such that the angle $\angle$BCA is a right angle. Then the value of f will be

(A) AB/OC²                                                     (B) (AC)(BC)/OC
(C) (OC)(AB)/AC+BC                                    (D) OC²​/AB