(a) Prior to the effective date of retirement, but not thereafter, except as provided in subsection (c) of this section, a member may elect to receive retirement income payments in the normal form, or the actuarial equivalent of the normal form from the following options:
(1) Joint and Survivor Annuity. A life annuity payable during the joint lifetime of the retirant and his or her beneficiary who is a natural person with an insurable interest in the retirants life. Upon the death of the retirant, the benefit shall continue as a life annuity to the survivor in an amount equal to 50 percent, 66 and two-thirds percent, 75 percent, or 100 percent of the amount paid while both were living as selected by the member. If the beneficiary dies first, the monthly amount of benefits may not be reduced, but shall be paid at the amount that was in effect before the death of the beneficiary. If the retiring member is married, the spouse shall sign a waiver of benefit rights if the beneficiary is to be other than the spouse.