In a face centered cubic structure, every atom has 12 neighbors. which arrangement of balls serves as the best model for this structure? a) 8 balls at the corners of a cube, 6 balls in the centers of the cubes faces. b) 8 balls at the corners of a cube. c) 8 balls at the corners of a cube, and one ball in the center of the cube. d) 12 balls arranged equally apart from eachother around a circle.