Only the following persons are eligible to be made the beneficiaries of, or to receive payments under, an annuity elected under this subchapter by a member of the armed forces:
((1)) The spouse of the member on the date when the member is retired or becomes entitled to retired or retainer pay or, if the member was already retired or entitled to retired or retainer pay on , the spouse on that date.
((2)) The children of the member who are—
((A)) unmarried;
((B)) under eighteen years of age, or incapable of supporting themselves because of a mental defect or physical incapacity existing before their eighteenth birthday, or at least eighteen, but under twenty-three, years of age and pursuing a full-time course of study or training in a high school, trade school, technical or vocational institute, junior college, college, university, or comparable recognized educational institution;
((C)) legitimate or adopted children of, or stepchildren in fact dependent for their support upon, the member;
((D)) living on the date when the member is retired or becomes entitled to retired or retainer pay or, if the member was already retired or entitled to retired or retainer pay on , living on that date; and
((E)) born on or before the date prescribed in clause (D).