@eesiginfo: if you're contending that there might be multiple light sources (and I don't think you are), there would be multiple shadows. That's the thing: that photo would look the same whether it was taken on the moon with a single bright source, or on an Arizonan sound stage with a single bright source (although they'd struggle to emulate the clarity in the distance on the sound stage).
Single shadows falling in different directions in one photo can *only* be caused by a single light source and either perspective or topography. There is no alternative. Multiple light sources produce multiple shadows.