I'd settle for B....the human eye is very adaptive when it comes to lighting, the same colors look natural to the eye in daylight or tungsten light, yet we know how different they will appear on film. It may well be that the shadows of the dress picked up a blue cast from the skylight, especially if it as slight as you say, and the faces and grass look OK.

What people do notice on a photo, however, is whether the skin tones appear correct...or at least flattering.

The point about optical brighteners in fabric is also very valid.