J=0 L and S are parallel and pointing in opposite directions. This is quite clear because these are the same vectors just pointing in the opposite directions, its just like walking one way and returning the same distance in the opposite direction. Resulting in a zero length vector.
J=2 L and S are parallel and pointing in the same direction. Just like the same example before but now you travel a distance in one direction and then you do it again so you end up with dubbel the distance you originally did.
J=1 L and S are perpendicular to each other. only option left