; (3) the Authority may, with respect to those employees who were hired before the date of enactment of this Act but who had yet to accumulate a total of 5 years of employment with the Authority, determine a benefits plan which may include a combination of a defined benefit and a defined contribution; and (4) the Authority shall, for all employees not enrolled in the Authority’s pension system on the date of enactment of this Act, provide defined contribution retirement plans.