A man observes a tower AB of height `h` from a point `P` on the ground. He moves a distance `d` towards the foot of the tower and finds that the angle of elevation is doubled. He further moves a distance "`(3d)/(4)` in the same direction and finds that the angle of elevation is three times that of at the point `P` .then (A) `30h^(2)=35d^(2)` (B) `35h^(2)=36d^(2)` (C) `36h^(2)=35d^(2)` (D) `36h^(2)=35d^(2)`