(a) Of gas, water, electricity or sewage disposal services by municipalities to such persons as said municipalities are authorized by law to serve;
(b) Of gas or electricity by cooperative gas or electric power associations to the members thereof as consumers, except as provided by Section 77-3-17, where service is rendered in a municipality;
(c) Of water or sewage disposal service by nonprofit corporations or associations where the governing body of such corporation or association is elected by the consumers thereof or appointed by the county board of supervisors; or
(d) Of water by districts organized under the provisions of Chapter 45, Laws of 1966-1967, Extraordinary Session.