Sec. 3. As used in this chapter, "applicable fund" means the following:
(1) For members of the 1925 fund, the 1925 fund.
(2) For members of the 1937 fund, the 1937 fund.
(3) For members of the 1953 fund, the 1953 fund.
(4) For members of the 1977 fund, the 1977 fund.