With no explanation, chose the best option from "A", "B", "C" or "D". making of competent parents.” (citing Troxel v. Granville, 530 U.S. 57, 67-69, 120 S.Ct. 2054, 147 L.Ed.2d 49 (2000))). We have further held that it is the party opposing termination of the guardianship who bears the burden of proving that the petitioning parent is currently unfit to regain custody of the child. Guardianship of David C., 2010 ME 136, ¶¶ 4, 7, 10 A.3d 684. [¶ 12] Although the Legislature has established the standard of a preponderance of the evidence for addressing the best interest of the child.in a proceeding to terminate a guardianship, neither we nor the Legislature has made clear what specific standard of proof the existing guardian must meet in proving the petitionin 174-75 (2010) (same); In re Guardianship of D.J., 268 Neb. 239, 682 N.W.2d 238, 243-46 (2004) (<HOLDING>). [¶ 13] We need not decide the applicable

A: holding that the guardianship must terminate unless the guardian proves by clear and convincing evidence that the petitioning parent is either unfit or has forfeited the right to custody
B: holding that on a parents petition the guardianship must terminate unless the guardian proves by clear and convincing evidence that terminating the guardianship would result in physical or emotional harm to the child
C: holding custody and guardianship of child whose natural parent is adjudicated unfit mandatorily vests with social services
D: recognizing that the child custody act required that the natural parent presumption must be seriously considered and heavily weighted in favor of the parent but that the presumption is rebutted if the clear and convincing evidence establishes that the best interest of the child is served by awarding custody to the third party
A.