(a) An eligible employee shall elect to:
(1) join a pension or retirement system in accordance with the provisions of this Division II applicable to that system; or
(2) participate in the program.
(b) An eligible employee shall:
(1) make an election under this section in writing; and
(2) file the election with the Board of Trustees and the employing institution at commencement of employment.
(c) An eligible employee’s election under this section is a one–time, irrevocable election.
(d) The effective date of the election shall be the day of commencement of employment.