(a)  A prospective adoptive parent may file a petition for adoption pursuant to Article 3 of this Chapter only if a minor has been placed with the prospective adoptive parent pursuant to Part 2 of Article 3 of this Chapter unless the requirement of placement is waived by the court for cause.
(b)  Except as authorized by Articles 4 and 6 of this Chapter, the spouse of a petitioner must join in the petition, unless the spouse has been declared incompetent or unless this requirement is otherwise waived by the court for cause.
(c)  If the individual who files the petition is unmarried, no other individual may join in the petition.