I have a test where I am given the following article, what is an answer for the question: What are the names of the performers who were prevented from preforming songs they had submitted? ?  SVT selects performers for the entries. Artists who perform the demo of a song automatically enter the competition; they must perform their songs if suitable alternate performers cannot be found. The artists' songs risk disqualification if they refuse. In the past, this rule led to the disqualification of, among others, Carola's "När löven faller" in 2003 and Stephen Simmonds's "So Good" in 2006. SVT may also give songs to other performers without considering the interests of the demo artist. This prevented the Brandsta City Släckers (in 2004) and Pernilla Wahlgren (in 2005) from performing the songs they had submitted. Replacements for disqualified songs fare unpredictably at the competition. In 2006, "Naughty Boy" by Hannah Graaf (the replacement for Simmonds' song) finished second to last in its semi-final. In 2002 and 2007, by contrast, the replacements performed by Jan Johansen and Måns Zelmerlöw reached the final ten. The contestants that will perform the twenty-eight qualifiers from the preselection are announced in late November. Singer-songwriters are common. As such, artists often confirm that they will participate before the official announcement. The wildcard (joker) system was introduced in 2004 to diversify the music featured. Four artists, one in each semi-final, were invited by SVT to enter a song of their choice into the competition, provided it does not breach the rules. The wildcard songs and artists were announced in January. Since the wildcards' introduction, three have won the competition. In 2011 there were 15 wildcards. The wildcard system was discontinued in 2013.
Answer:
Pernilla Wahlgren