A. The board in its discretion may extend for a reasonable period the time within which any course of instruction shall be completed by any student upon the showing of good cause that shall include but is not limited to:
(1) Interruptions in completing the course of instruction caused by any illness of or accident to the student;
(2) Enrollment and attendance in any secondary school or institute of higher learning; or
(3) Service in the armed forces of the United States.
B. Application for an extension of time pursuant to this Section shall be made to the board in writing.