Cord scrambling. Arcs show where one power cord passes over another, thus in (B), the cords with no arcs are below all others, while those in power outlets 1 and 2 are above all others. The devices in (B) can be removed in the order (1 or 2) before (3 or 5) before 4, which must be removed last (numbering the devices in left-to-right order of power outlets). In (C), device 5 may be removed first, then device 3, but the remaining devices are tangled. In (D), all devices are tangled.