The center of mass can "see" (in straight lines) all points within the shape vs. the center of mass is not located in a region where it can see (in straight lines) all points.
Another way of thinking about the solution is considering whether a light source placed at the center of mass of a given example would illuminate the whole shape.
CROSSREFS
Every left for this Problem would be will be a left example for both BP367 and BP368.