单项选择题

TEXT C
In the summer of 999, Leif Erikson voyaged to Norway and spent the following winter with King Olaf Tryggvason. Substantially the same account is given by both the Saga of Eric the Red and the Flat Island Book. The latter says nothing about Leif’s return voyage to Greenland, but according to the former it was during this return voyage that Leif discovered America. The Flat Island Book, however, tells of another and earlier landfall by Biarni, the son of a prominent man named Heriulf, and makes that the inspiration for the voyage to the new land by Leif. In brief, like Leif, Biarni and his companions sight three countries in succession before reaching Greenland, and to come upon each new land takes 1 "doegr" (time record) more than the last until Biarni comes to land directly in front of his father’s house in the last-mentioned country.
This narrative has been rejected by most later writers, and they may be justified. Possibly, Biarni was a companion of Leif when he voyaged from Norway to Greenland via America, or it may be that the entire tale is but a garbled account of that voyage and Biarni another name for Leif. It should be noted, however, that the stories of Leif’s visit to King Olaf and Biarni’s to that king’s predecessor are in the same narrative in the Flat Island Book, so there is less likelihood of duplication than if they were from different sources. Also, Biarni landed on none of the lands he passed, but Leif apparently landed on one, for he brought back specimens of wheat, vines, and timber. Nor is there any good reason to believe that the first land visited by Biarni was Wineland. The first land was "level and covered with woods," and "there were small hillocks upon it." Of forests, later writers do not emphasize them particularly in connection with Wineland, though they are often noted incidentally; and of hills, the Saga says of Wineland only that "wherever there was hilly ground, there were vines."
Additionally, if the two narratives were taken from the same source we should expect a closer resemblance of Helluland. The Saga says of it: "They found there hellus (large flat stones)." According to the Biarni narrative, however, "this land was high and mountainous." The intervals of 1, 2, 3, and 4 "doegr" in both narratives are suggestive, but mythic formulas of this kind may be introduced into narratives without altogether destroying their historicity. It is also held against the Biarni narrative that its hero is made to come upon the coast of Greenland exactly in front of his father’s home. But it should be recalled that Heriulfsness lay below two high mountains which served as landmarks for navigators.
I would give up Biarni more readily were it not that the story of Leif’s voyage contained in the supposedly more reliable Saga is almost as amazing. But Leif’s voyage across the entire width of the North Atlantic is said to be "probable" because it is incorporated into the narrative of a preferred authority, while Biarni’s is "improbable" or even "impossible" because the document containing it has been condemned.
All of the following are mentioned as similarities between Leif Erikson’s voyage and Biarni’s voyage EXCEPT that ______.