A. Notwithstanding any other provision of this article, a retired member or beneficiary who is entitled to a benefit under this article shall receive at least a minimum monthly benefit that is computed pursuant to subsection B of this section if the retired member or beneficiary is at least seventy-five years of age and if the retired member or beneficiary is any of the following:

1. 1. Retired from ASRS with at least twenty years of credited service.
2. 2. A beneficiary of ASRS who is receiving benefits derived from a retired member who had at least twenty years of credited service.
3. 3. A member with at least twenty years of service who irrevocably revokes the receipt of benefits determined on the basis of membership in the defined contribution program administered by ASRS and who elects to receive benefits under this article.
4. 4. A beneficiary who is receiving benefits derived from a retired member who had at least twenty years of service, who irrevocably revoked the receipt of benefits determined on the basis of membership in the defined contribution program administered by ASRS and who elected to receive benefits under this article.

B. The minimum monthly benefit provided by subsection A of this section:

1. 1. For retired members, is $600.
2. 2. For beneficiaries, is the amount determined by paragraph 1 of this subsection and reduced in accordance with the option chosen by multiplying the amount determined by paragraph 1 of this subsection by the actuarial figure for the option chosen and by the percentage of the option chosen.