A child annuity ends with the earliest of--
(a) The last day of the month before the month in which the child marries;
(b) The last day of the month before the month in which the child dies;
(c) The last day of the month before the month in which the child attains age 18 if the child is not eligible for an annuity as a disabled or student child;
(d) The last day of the last month in which the child is considered a full-time student, as defined in part 216 of this chapter, if the child is a full-time student age 18 through 19; or
(e) The last day of the second month after the month in which the child's disability ends, if the child is over age 18.