When a member desires to provide both the annuity provided by Option 1 and Option 2, he may elect amounts that, in total, meet the limitations specified in Sec. 48.201. The cost of each annuity, and the amount of each annuity shall be determined separately. A member may not elect the combination of Options 1 and 3 or Options 2 and 3 in any case. The combined amount of the annuities may not be more than 50 per centum nor less than 12\1/2\ per centum of his retired pay. In no case may less than a $25 per month combined annuity be provided.