Question: What is the country of the singer of the song Oah?

full_context: Document 1: Oah: "Oah" is a song by Norwegian singer–songwriter Alexander Rybak. It is the first single released from his second album "No Boundaries". It was released on 8 June 2010.
Document 2: Alt for Norge: Alt for Norge ("All for Norway", though marketed in the United States as "The Great Norway Adventure") is a Norwegian reality television series which debuted in 2010 and appears on TVNorge and hosted by . The reality show features Norwegian Americans participating in challenges relating to Norwegian history and culture, competing to win a reunion with their distant Norwegian relatives. The original Norwegian concept has also been exported to Sweden and Denmark.
Document 3: Christmas Tales: Christmas Tales is the fourth studio album and first Christmas album by the Belarusian-Norwegian artist Alexander Rybak, it released on the November 23, 2012 in Norway. It has peaked to number 34 on the Norwegian Albums Chart.
Document 4: Greece: Greece participated in the Eurovision Song Contest 35 times after its debut at the 1974 Contest. In 2005, Greece won with the song "My Number One", performed by Greek-Swedish singer Elena Paparizou. The song received 230 points with 10 sets of 12 points from Belgium, Bulgaria, Hungary, the United Kingdom, Turkey, Albania, Cyprus, Serbia & Montenegro, Sweden and Germany and also became a smash hit in different countries and especially in Greece. The 51st Eurovision Song Contest was held in Athens at the Olympic Indoor Hall of the Athens Olympic Sports Complex in Maroussi, with hosted by Maria Menounos and Sakis Rouvas.
Document 5: Love Me (Lena Meyer-Landrut song): "Love Me" is a song by German singer Lena Meyer-Landrut, co-written by her and entertainer Stefan Raab. It was one of three songs performed by Meyer-Landrut in the final of Unser Star für Oslo (Our Star for Oslo), the national pre-selection programme for Germany's entry to the Eurovision Song Contest 2010. However, the audience chose "Satellite" to be her designated song for the contest in Oslo. "Love Me" was made available for digital download on 13 March 2010 and is also featured on Meyer-Landrut's maxi single "Satellite". The song subsequently charted in Germany, Austria and Switzerland, reaching peak positions of #4, #28 and #39 respectively.
Document 6: Spark (Marit Larsen album): Spark is the third album from Norwegian singer-songwriter Marit Larsen, and was released on November 18, 2011. The information was made available via Marit Larsen's Tumblr page. On 31 July 2011 Marit Larsen began to post information about her third album on her Tumblr. On 7 October 2011 she announced the name of the album and track list. The first single, "Coming Home" had premiered on NRK P3 and on her Facebook page on 15 October. The album produced two singles; "Coming Home" and "Don't Move". The album spawned 2 number one songs in the Philippine Top 100 Songs Chart where in "Coming Home" stayed atop for 4 consecutive weeks, which gave Marit her first number one song in the Philippines as a solo artist and her non-single song "Last Night" stayed for 2 consecutive weeks in the early 2012, serving as her second number one song.
Document 7: Eurovision Song Contest 2018: The Eurovision Song Contest 2018 was the 63rd edition of the annual Eurovision Song Contest. It took place for the first time in Portugal following the country's first victory at the 2017 contest in Kiev, Ukraine with the song ``Amar pelos dois '', performed by Salvador Sobral. The contest was held at the Altice Arena in Lisbon, and consisted of two semi-finals on 8 and 10 May, and the final on 12 May 2018. The three live shows were hosted by Filomena Cautela, Sílvia Alberto, Daniela Ruah and Catarina Furtado.
Document 8: Norway in the Eurovision Song Contest 2010: Norway hosted the Eurovision Song Contest 2010 at the Telenor Arena in Oslo, after Alexander Rybak won the 2009 Contest with "Fairytale".
Document 9: Slovenia in the Eurovision Song Contest 2010: Slovenia selected its entry for the Eurovision Song Contest 2010, which was held in Oslo, Norway, through the EMA contest, organised by Radiotelevizija Slovenija (RTV SLO). The winner of the contest, held on 21 February, was Ansambel Roka Žlindre and Kalamari with the song "Narodnozabavni rock" (Popular folk rock), which received 15,907 votes, almost five times as many votes as runner-up Nina Pušlar.
Document 10: Tam, de nas nema: Tam, de nas nema (; "Wherever We Aren't") is the debut studio album of the popular Ukrainian rock group Okean Elzy. Svyatoslav Vakarchuk is the lead vocalist and songwriter for most of the lyrics on this album. It was released in 1998 by the Kiev-based record label Lavina Music.
Document 11: Enta Menni: Enta menni is Yara's second music disc album and was released in the summer of 2008. It is a Melody Music production. Two years after her breakthrough with her duet "Akhdny maak" with famous singer Fadl Shaker the album proved to be a bigger success than her first album released in 2005 "Twassa Feyi" isn't much different from her usual; romantic songs that bring the world of imagination and fantasy to the listener, however the album lyrics touches on a more "Artistically Mature" Yara especially since this would be the first album she sings in the Khaliji dialect. The album contains 10 songs in the different Arabic dialects; Egyptian, Lebanese and Khaliji. The title track "Enta Menni" ("You are part of Me") which is an Egyptian song was one of the most successful songs of the year.
Document 12: Germany in the Eurovision Song Contest 2010: Germany is the Eurovision Song Contest 2010 winner, which was held in May 2010 in Bærum, Norway. The country's entry was selected in a series of competitive heats and a national final – Unser Star für Oslo 2010 – which was organised jointly by the public broadcasters ARD and NDR and the private television channel ProSieben, together with the three-time Eurovision participant for Germany (as singer and/or songwriter) and music producer, Stefan Raab.
Document 13: Roll with the Wind: "Roll With the Wind" is a song by Norwegian singer–songwriter Alexander Rybak from his debut studio album, "Fairytales". "Roll With the Wind" was written by Mårten Eriksson and Lisa Eriksson and produced by Amir Aly.
Document 14: United Kingdom in the Eurovision Song Contest: Year Location Venue Presenters 1960 London Royal Festival Hall Katie Boyle 1963 BBC Television Centre 1968 Royal Albert Hall 1972 Edinburgh Usher Hall Moira Shearer Brighton Brighton Dome Katie Boyle 1977 London Wembley Conference Centre Angela Rippon 1982 Harrogate Harrogate International Centre Jan Leeming 1998 Birmingham National Indoor Arena Ulrika Jonsson and Terry Wogan
Document 15: The Chase (Marit Larsen album): The Chase is the second album from Norwegian singer-songwriter Marit Larsen. It was released on October 13, 2008. The first single of this album entitled "If a Song Could Get Me You" was made available via Marit Larsen's Myspace page on August 11, 2008.
ground_truth: Norway
sub_queries: Oah >> performer Answer: Alexander Rybak
Alexander Rybak >> country of citizenship Answer: Norway