Each new state employee who may be entitled to become eligible for membership in the state employees retirement system, part B, shall, at the time of commencement of his employment, elect (a) to become a member, when eligible, of the state employees retirement system, part B, integrated with Social Security, in which event he shall make all the payments required of such a part B employee and receive all the benefits of such a part B employee; or (b) to become a member, when eligible, of the state employees retirement system, part A, plus Social Security coverage, in which event he shall make all the payments required for Social Security and of such a part A employee and receive all the benefits of such part A and Social Security. Any such employee, who fails to make an election within six months after employment, shall be deemed to have elected to become a member of the state employees retirement system part B, pursuant to subdivision (a) of this section, unless such employee qualifies for, and has elected to become a member of, either the Teachers’ Retirement Association in accordance with the provisions of subsection (g) of section 5-160 or an alternate retirement program as authorized by subsections (u) and (v) of section 5-154, section 5-156, this section and subsection (g) of section 5-160. No such election shall be changed after six months’ employment except as provided in section 5-158b or 5-158c. Each employee not presently a member of the state employees retirement system shall have an opportunity to elect or reject membership in the period between October 1, 1973, and December 31, 1973, in accordance with rules to be prescribed by the State Employees Retirement Commission. The requirements of this section shall not apply to state employees in positions funded in whole or in part by the federal government as part of any public service employment program, on-the-job training program or work experience program.