I assume A, B, C and D are regions. We can represent them on a straight line, s or s axis. Mark points from left to right: Mark -18 and -2 as two points on the line. Region D is the leftmost region and sits over the line to the left of point -18; region C lies to the right of point -18, and next to it, or associated with the same region, is region B; both C and B lie to the left of point -2 and to the right of point -18; to the right of point -2 we have region A. The question doesn't ask for anything else.