We know that the five artifacts each originated from Iceland, Norway, and Sweden. There is nothing in the stimulus which requires that at least one artifact originated from each country.
Therefore, it is entirely possible that four artifacts originated in Sweden and one originated in Iceland. See the following setup:
Sweden: V W X Y Iceland: Z Norway: _
Notice that this setup meets all of the conditions imposed by the stimulus. Each artifacts originated in Iceland, Norway, or Sweden.
1) W and Y originated in the same country as both originated in Sweden. 2) X originated in Sweden. 3) More of the artifacts originated in Iceland (1) than in Norway (0). 4) V did not originate in Iceland, so this condition does not apply.
Hope this helps! Please let us know if you have any further questions.