Information:  - Sigurd Hart or Sigurd Hjort was a legendary king of Ringerike in Norway, who appears in "Ragnarssona þáttr" and in "Halfdan the Black's saga".  - Norway (; Norwegian: (Bokmål) or (Nynorsk); Sami: "Norgga"), officially the Kingdom of Norway, is a sovereign and unitary monarchy whose territory comprises the western portion of the Scandinavian Peninsula plus the island Jan Mayen and the archipelago of Svalbard. The Antarctic Peter I Island and the sub-Antarctic Bouvet Island are dependent territories and thus not considered part of the Kingdom. Norway also lays claim to a section of Antarctica known as Queen Maud Land. Until 1814, the Kingdom included the Faroe Islands (since 1035), Greenland (1261), and Iceland (1262). It also included Shetland and Orkney until 1468. It also included the following provinces, now in Sweden: Jämtland, Härjedalen and Bohuslän.  - Ragnhild Sigurdsdotter was the daughter of Sigurd Hart of the Dagling clan .  - Halfdan the Black (Old Norse: "Halfdanr Svarti") ( ) was a ninth-century king of Vestfold. He belonged to the House of Yngling and was the father of Harald Fairhair, the first king of Norway.  - The Dagling or "Dögling" dynasty was a legendary clan of the petty kingdom Ringerike in what today is Norway. It was descended from a Dag the Great.    Given the paragraphs above, decide what entity has the relation 'child' with 'harald fairhair'.
A:
ragnhild sigurdsdotter