If in the following figure (not to scale), $$\angle DAB + \angle CBA = 90^\circ, BC = AD, AB = 20$$ cm, $$CD = 10$$ cm then the area of the quadrilateral ABCD is:

A

120 $$cm^2$$

B

75 $$cm^2$$

C

100 $$cm^2$$

D

150 $$cm^2$$