Question: The best selling single of John Lennon's solo career was used as a teference by who to erect a memorial?

Context paragraphs:
Kimi ni Aitakute: "Kimi ni Aitakute" (君に逢いたくて ) is a single released by Gackt on October 27, 2004.  It peaked at second place on the Oricon weekly chart and charted for seventeen weeks.  In 2004, it was the 96th best selling single of the year, with sales of 98,335 copies.  As it charted for 17 weeks, it sold 124,280 copies, making it Gackt's ninth best selling single.

Imagine (John Lennon song): "Imagine" is a song written and performed by English musician John Lennon.  The best-selling single of his solo career, its lyrics encourage the listener to imagine a world at peace without the barriers of borders or the divisions of religion and nationality, and to consider the possibility that the whole of humanity would live unattached to material possessions.

Juno Award for Best Selling Single: The "Juno Award for Best Selling Single" was awarded from 1975-1993 for the best selling single in Canada.  It was also known as "Best Selling International Single" and "International Single of the Year".

Another World (Gackt song): "Another World" is the ninth single by Japanese musical artist Gackt.  It was released on September 5, 2001 and peaked at second place on the Oricon weekly chart and charted for seventeen weeks.  In 2001, with sales of 255,640 copies, it was the 74th best selling single of the year.  It is Gackt's best selling single with 285,550 copies sold.

Imagine Peace Tower: The Imagine Peace Tower (Icelandic: "Friðarsúlan" , meaning "the peace column") is a memorial to John Lennon from his widow, Yoko Ono, located on Viðey Island in Kollafjörður Bay near Reykjavík, Iceland.  It consists of a tall tower of light, projected from a white stone monument that has the words "Imagine Peace" carved into it in 24 languages.  These words, and the name of the tower, are a reference to Lennon's campaign for peace, and his song "Imagine".

Cheryl discography: The discography of English recording artist Cheryl consists of four studio albums, one extended play, nine singles (excluding three as a featured artist), and fourteen music videos.  Cheryl's first foray into a solo music career occurred when she featured on will.i.am's "Heartbreaker".  After having streetdancing lessons during the filming of "Passions of Girls Aloud" series, Cheryl was picked to appear in the song's video.  She was later asked to sing the female vocals on the UK release of the track, which reached number four in the United Kingdom and sold over 250,000 copies, giving the single a silver certificate by the BPI.  It was the 31st best selling single of 2008.  Cheryl's solo career began in October 2009 with the release of "Fight for This Love", the lead single from her debut studio album, "3 Words".  The track saw Cheryl achieve her first solo number-one single when it topped the UK chart, while also attaining international chart success; peaking within the top 10 in the likes of France, Germany and the Netherlands.  The parent album debuted at number one in the UK with sales of 125,271.  On 6 November 2009 the British Phonographic Industry (BPI) certified the album platinum.  It has since gone 3× Platinum, with sales of over 1,000,000 copies. " 3 Words" is both the opening and title song from her debut studio album.  It was released in the UK and Ireland on 20 December 2009 went on to become Fernandez-Versini's second consecutive UK top-five and Irish-top ten hit.  It was also a top five hit in Australia and has since been certified platinum by the Australian Recording Industry Association and gold by the British Phonographic Industry. " Parachute" was released on 11 March 2010 as the album's third and final single.  "Parachute" became Cheryl's third consecutive solo UK top five hit, and her third Irish top 10 hit.  It was nominated for a Brit Award in 2011.

Alone (B'z song): Alone is the ninth single by B'z, released on October 10, 1991.  This song is one of B'z many number-one singles in Oricon chart.  The single was re-released in 2003, and re-entered at #8.  It sold over 1,127,000 copies according to Oricon.  It was used as the drama Hotel Woman's theme song.  The song was the 10th best selling single of 1991 and the 56th best selling single of 1992, making their only single to chart for two years in the yearly charts.

Metamorphoze: "Metamorphoze" (Metamorphoze ～メタモルフォーゼ～ , Metamorufōze ) is a single released by Gackt on May 25, 2005.  It peaked at second place on the Oricon weekly chart and charted for thirteen weeks.  In 2005, it was the 62nd best selling single of the year, with sales of 156,709 copies, making it to be Gackt's fourth best selling single.  Both, A-side and B-side are also featured in the "Mobile Suit Zeta Gundam" movie "Heir to the Stars".  The music video combines footage from the anime with live-action sequences of Gackt piloting in a UC 0093 ("" era) spacesuit and linear seat (a type of cockpit setup in the "Gundam" series).

Lennon Legend: The Very Best of John Lennon: Lennon Legend: The Very Best of John Lennon is the third official compilation album of John Lennon's solo career, coming after 1975's "Shaved Fish" and 1982's "The John Lennon Collection".  Because neither collection spanned Lennon's releases up to and including 1984's "Milk and Honey", "Lennon Legend: The Very Best of John Lennon" – considered the definitive Lennon retrospective – was compiled to rectify the situation.  It was released in the UK in 1997 through Parlophone and early 1998 in the US by EMI Records.

Redemption (Gackt song): "Redemption" is a single released by Gackt on January 25, 2006.  It peaked at third place on the Oricon weekly chart and charted for twelve weeks.  In 2006, it was the 83rd best selling single with sales of 124,955 copies, making it to be Gackt's eighth best selling single.  The "Longing" and "Redemption" were theme songs of the video game "".

Supporting paragraphs: Imagine Peace Tower Imagine (John Lennon song)
Answer: Yoko Ono