A filled-in circle represents a " pie graph" with the specific trait in a pedigree chart. I would conclude to say that the answer would probably be graph, and the reason why I would then say so would be because, first,a pie graph would obviously look like a circle, and not only that, but also, a pedigree chart would also have a relation with the fact that it would be a associating with a "pie graph", and based on this, this would then be my reasoning's.