On the final hearing the board of supervisors shall make changes in the proposed boundaries of the proposed district as may be deemed advisable and shall describe the boundaries of the proposed district. In doing this:
(a) No land included in the proposed district in the petition which will be benefited by the proposed district shall be excluded.
(b) No land which will not in the judgment of the board be benefited by the district shall be included.
(c) Upon the application of any person whose land was not included in the petition but whose land will be benefited by the proposed district, the land may in the discretion of the board be included.