The angle of elevation of the top of an unfinished tower at a point distant 78 m from its base is $$30^{\circ}$$. How much higher must the tower be raised (in m) so that the angle of elevation of the top of the finished tower at the same point will be $$60^{\circ}$$?

A

52\sqrt{3}

B

26\sqrt{3}

C

78\sqrt{3}

D

80