Q: In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.
Passage: In Rainbows is the seventh studio album by English rock band Radiohead. It was self-released on 10 October 2007 as a pay-what-you-want download, followed by a physical release internationally by XL Recordings in December 2007 and in the United States on 1 January 2008 by TBD Records. It was Radiohead's first release after their recording contract with EMI ended with their previous album Hail to the Thief (2003).
Radiohead worked on In Rainbows for more than two years, beginning in early 2005. In 2006, after their initial recording sessions with new producer Spike Stent proved fruitless, the band toured Europe and North America performing In Rainbows material before re-enlisting longtime producer Nigel Godrich. The album is more personal than previous Radiohead albums, with singer Thom Yorke describing most of the songs as his versions of "seduction songs". Radiohead incorporated a variety of musical styles and instruments, using electronic instruments, string arrangements, piano, and the ondes Martenot.
The album's pay-what-you-want release, the first for a major act, made headlines around the world and sparked debate about implications for the music industry. The physical release debuted at number 1 on the UK Albums Chart and the US Billboard 200, and had sold over three million copies worldwide by October 2008. The album received critical acclaim and was ranked one of the best albums of 2007 and of the decade by various publications. It won two Grammy Awards for Best Alternative Music Album and Best Boxed or Special Limited Edition Package. In 2012, Rolling Stone placed In Rainbows at number 336 on their updated list of the 500 Greatest Albums of All Time.
A:
What albums physical release debuted at number 1 on the UK Albums Chart?