The angles of elevation of the top of a building measured from two points A, B on the horizontal ground and on the sameside of the building are respectively $$30^\circ, 60^\circ$$. If A, B and the foot of the building are collinear and AB = 400 metres, then the height of that building, in metres, is

A

$$200\sqrt{3}$$

B

200

C

$$100(\sqrt{3} - 1)$$

D

$$100(\sqrt{3} + 1)$$