In the Grimm tale 'Mary's Child,' which forbidden numbered door does the girl open?

In the Grimm tale “Mary’s Child,” the girl opens the forbidden thirteenth door.

The story, also known as “Our Lady’s Child,” is KHM 3 and was first published in the Grimms’ 1812 collection. The Virgin Mary takes in a poor woodcutter’s daughter and raises her in Heaven, where she gives the girl keys to twelve doors and forbids her to open the thirteenth.

Behind the first twelve doors are the Apostles. Behind the forbidden door is the Trinity, and the girl’s finger becomes marked with gold. She denies opening the door, and her disobedience and repeated lying lead to punishment before the tale’s final restoration.

The number is easy to confuse with other forbidden-room stories, especially “Bluebeard” and “Fitcher’s Bird,” which also feature locked doors and concealed discoveries. “Mary’s Child” is additionally classified as ATU 710, “Our Lady’s Child,” and its religious framework distinguishes it from those better-known parallels.