(a) Unless the articles or bylaws provide otherwise, and except as provided in paragraphs (b), (c), and (d), if a vacancy occurs on the board of directors, including a vacancy resulting from an increase in the number of directors:
(1) the members with voting rights, if any, may fill the vacancy; or
(2) the remaining members of the board, though less than a quorum, may fill the vacancy.
(b) If a vacant office was held by a director elected by a class, chapter, or other organizational unit or by region or other geographic grouping, only members with voting rights of the class, chapter, unit, or grouping are entitled to vote to fill the vacancy.
(c) If a vacant office was held by an appointed director, only the person who appointed the director may fill the vacancy.
(d) A vacancy that will occur at a specific later date may be filled before the vacancy occurs but the new director may not take office until the vacancy occurs.