Julia is using this figure to prove that triangle ABC is an isosceles triangle. First, she used the converse of the perpendicular bisector theorem and the definition of perpendicular lines to determine that CE is the perpendicular bisector of AB. A horizontal line A B, and a vertical line C D are intersecting at point E. The points A B C form an isosceles triangle. What could be the next step of a valid proof? A. AE = CE because of the perpendicular bisector theorem B. AC = BC because of the perpendicular bisector theorem C. CE = AB because of the perpendicular bisector theorem D. CE = BC because of the perpendicular bisector theorem