computer graphics – Ray tracing tree

Let’s suppose that we have a light source. Which of the following are correct for the tree of recursive ray-tracing (ray tree) that create when we make the colors for each pixel in the screen.
Which of the following are correct:

a) if scene contains of one non-convex polyhedron (random shape and position) then we can’t have a bound for the height of tree in general. (Even the camera is out of range of object)

b) if scene contains of two convex polyhedrons then the height of tree can be at most 2 independent of the position of camera and the position of objects (the camera is out of range of the two objects)

c) if scene contains of two non-convex polyhedrons (random shape and position) then we can’t have a bound for the height of tree in general. (Even the camera is out of range of object)

d) if scene contains of one convex polyhedron then the height of tree can be at most 1 independent of the position of camera and the position of objects (the camera is out of range of the object)

e) if scene contains of one non-convex polyhedron then the height of tree can be at most 1 independent of the position of camera and the position of object (the camera is out of range of the object)

I am confused about the choice of polyhedrons (convex and non-convex), i can’t understand the difference.
Also i don’t understand how the camera out of range of objects can help to make the ray tree.