With the busy print, I don't think you want a sharp contrast, or anything with much of a pattern. I really like the third fabric from the top. Is that C? Anyway, the point is to make a silhouette, not grab all of the attention away from the very beautiful background fabric. That lighter color will definitely work as a silhouette -- e.g. you can accomplish what you want to do. But it won't be so bold as to overwhelm the beautiful soft print. That's what I would do, but then, it's your choice.
Good Luck!