They're about the same on my monitor because the background in B looks only slightly darker. Nice shot, but the issue I think is not general background lightness, but that bright spot near the lower right corner. Darken that without making it look fake and it will be a great image regardless of whether the rest of the background is a little lighter or darker.
Neither. From a compositional viewpoint the image is two balanced with 2 flowers facing forward: one on each side. If the 3 flowers were facing forward, then the composition would be better.
I think the colors in B are a bit nicer though the clone stamping you did right under the B is slightly weird... Though that might be just my annoyingly perfectionist opinion.
Not enough variation to differentiate. In other words the slight cleaning of one over the other does not make your subject stand out more in one than the otherl