In this chapter:
(1) “Governmental unit” means a county, municipality, authority, district, or other political subdivision of the state.
(2) “Commission” means a regional planning commission, council of governments, or similar regional planning agency created under this chapter.
(3) “Region” means a geographic area consisting of a county or two or more adjoining counties that have, in any combination:
(A) common problems of transportation, water supply, drainage, or land use;
(B) similar, common, or interrelated forms of urban development or concentration; or
(C) special problems of agriculture, forestry, conservation, or other matters.