(a) Newly created directorships resulting from an increase in the number of directors elected or appointed at large, and vacancies among such directors for any reason, may be filled by vote of a majority of the directors then in office, regardless of their number, unless the certificate of incorporation or the by-laws provide that such newly created directorships or vacancies shall be filled by vote of the members.

(b) Vacancies among directors elected or appointed by special districts or membership sections, or by bondholders voting as a class, shall be filled by action of the persons entitled to vote thereon; except that, if a vacancy remains unfilled for six months after it occurs, and by reason of the absence, illness, or other inability of one or more of the remaining directors a quorum of the board cannot be obtained, the remaining directors, or a majority of them, may appoint a director to fill such vacancy.

(c) A director elected or appointed to fill a vacancy shall hold office until the next annual meeting at which the election of directors is in the regular order of business, and until his successor is elected or appointed and qualified.