(a) The commission shall adopt a pricing rule.
(b) In adopting the pricing rule, the commission shall:
(1) ensure that each price for a monopoly service remains affordable;
(2) ensure that each price for competitive service is not:
(A) unreasonably preferential, prejudicial, or discriminatory;
(B) directly or indirectly subsidized by a noncompetitive service; or
(C) predatory or anticompetitive; and
(3) require that each service recover the appropriate costs, including joint and common costs, of each facility and function used to provide the service.