Three identical metallic uncharged spheres A, B and C of radius a are kept on the corners of an equilateral triangle of side `d (d gt gt a)`. A fourth sphere (radius a) which has charge Q touches A and is then removed to a position for away. B is earthed and then the earth connection is removed. c is then earthed. The charge on C is
A. `(Qa)/(2d) ((2d-a)/(2d))`
B. `(Qa)/(2d) ((2d-a)/(d))`
C. `(Qa)/(2d) ((a-d)/d)`
D. `(2Qa)/(d) ((d-a)/(2d))`