(a) Except as provided in subsections (b) and (c) of this section, the 1983 GAM Table, the 1983 Table "a", and the 1994 GAR Table are recognized and approved as group annuity mortality tables for valuation and, at the option of the company, any one of these tables may be used for purposes of valuation for any annuity or pure endowment purchased on or after August 29, 1977, under a group annuity or pure endowment contract.(b) Except as provided in subsection (c) of this section, either the 1983 GAM Table or the 1994 GAR Table must be used to determine the minimum standard of valuation for any annuity of pure endowment purchased on or after January 1, 1987, under a group annuity or pure endowment contract.(c) The 1994 GAR Table must be used to determine the minimum standard of valuation for any annuity or pure endowment purchased on or after January 1, 2000, under a group annuity or pure endowment contract.