The angle of elevation of an aeroplane as observed from a point 30 m above the transparent water-surface of a lake is $$30^\circ$$ and the angle of depression of the image of the aeroplane in the water of the lake is $$60^\circ$$. The height of the aeroplane from the water-surface of the lake is

A

60 m

B

45 m

C

50 m

D

75 m