(a) Preferred evidence. Preferred evidence that a marriage has ended is—

(1) A certified copy of the decree of divorce or annulment; or

(2) Evidence of the death (See § 219.23) of a party to the marriage.

(b) Other evidence that a marriage has ended. If preferred evidence that the marriage has ended cannot be obtained, the claimant must explain the reason therefor and submit other convincing evidence that the marriage has ended.