The shape consists of 5 faces. One on the front, one on the back, one on the left of the shape, the other on the right, and of course the one on the bottom :) Hope it helped.
If something is perpendicular to something else, it intersects it at 90 degrees. So, it there is a bisector perpendicularly bisecting a segment, it means they are crossing at a 90 degree angle. Your answer should be B.
