If comparing market structures, when economies of scale are unimportant: (w) the most efficient form of market structure is a pure monopoly. (x) purely competitive industries and price discriminating monopolies are equally efficient. (y) price discriminating monopolies tend to be more efficient than purely competitive firms. (z) purely competitive industries tend to be more efficient than monopolies which do not price discriminate.
Can someone explain/help me with best solution about problem of Economics...