As given in the diagram, in $$\triangle ABC, \angle B > 90^\circ$$ and AD is perpendicular to BC. Then $$b^2 =$$

A

$$a^2 + c^2 - 2ax$$

B

$$a^2 + c^2 + 2ax$$

C

$$a^2 + c^2 + ax$$

D

$$a^2 + c^2 - ax$$