Need help resolving what I did wrong with this picture please

Using a Nikon D300 and a 12-24 f3.5-4.5 Nikon lens, I spot metered and focused on lady in front wearing green. I also firmly believe that I selected the one sensor that directly corresponded with the position of the lady in green. However nobody in the entire picture is in focus including the lady in Green. Instead the plant at the very bottom of picture is the only thing in focus.
Shot at f3.5, focal length =15.0 mm

below I posted two Pictures/links, one is normal size and one is very large.