A. has two mergers, the first being the shadow behind it taking attention away from the plant. The second is how the plants shadow is cut off.
Picture B has the plants full shadow but the other shadow is still there taking away from the plant.
I personally like A the best. Even though the plants shadow is cut off the plant itself and the other shadow are in the same area of the picture so your not trying to look at both sides of the picture itself.
trinitymitchell 