Three stones A, B and C are simultaneously projected from same point with same speed. A is thrown upwards, B is thrown horizontally and C is thrown downwards from a building. When the distance between stone A and C becomes 10 m, then distance between A and B will be
(A) 10 m
(B) 5 m
(C) $5\sqrt2$ m
(D) $10\sqrt2$ m
(A) 10 m
(B) 5 m
(C) $5\sqrt2$ m
(D) $10\sqrt2$ m