An endangered piece...

9/14/2009 – ... was the white bishop on b3, in view of the threat ...a5-a4, which has prompted White to resort to violent measures with 21.Bxd5. How would you assess the continuation? A) best, White wins a second pawn with a clear advantage;  B) not as strong as it looks, Black gets one pawn back by force, leaving him only marginally worse;  C) this move is actually a mistake, White loses a piece. The solution is here, but first ponder over it with a larger version of the diagram.