A divorced spouse annuity ends with the earliest of the last day of the month before the month in which the—

1. (a) Divorced spouse dies;
2. (b) Employee's entitlement to an annuity ends;
3. (c) Divorced spouse marries;
4. (d) Employee dies; or
5. (e) Divorced spouse becomes entitled to a retirement or disability insurance benefit under the Social Security Act based on a primary insurance amount which equals or exceeds the amount of the full divorced spouse annuity before reduction for age.