(1) Upon the adoption of the form of county government provided in this chapter, the legislative authority of the county and, except as provided in subsection (2) of this section, the executive authority of the county shall be vested in the five (5) member board of county commissioners.
(2)  The executive authority of the county may be vested in an executive board comprised of three (3) members of the board of county commissioners chosen by the board as a whole, in a manner to be determined by the board. If the board of county commissioners determines to vest the executive authority of the county in an executive board, the board shall identify the manner in which the executive board shall be chosen and shall choose the executive board within thirty (30) days of the adoption of the form of government provided in this chapter.