Question: Invisible was a song later included as a hidden track on which thirteenth U2 album?
Context: This list contains the names of albums that contain a hidden track and also information on how to find them.  Not all printings of an album contain the same track arrangements, so some copies of a particular album may not have the hidden track(s) listed below.  Some of these tracks may be hidden in the pregap, and some hidden simply as a track following the listed tracks.  The list is ordered by artist name using the surname where appropriate. "Invisible" is a song by Irish rock band U2.  Unveiled in a Super Bowl XLVIII television advertisement, it was available as a free digital download through the iTunes Store from 2–3 February 2014.  Bank of America gave $1 for each download of the track to (RED), an organisation co-founded by Bono, to fight AIDS.  Since 4 February, it has been available as a paid download, with all the proceeds also going to (RED).  The song was later included as a hidden track on the deluxe edition of the group's 2014 studio album "Songs of Innocence". This list contains the names of albums that contain a hidden track and also information on how to find them.  Not all printings of an album contain the same track arrangements, so some copies of a particular album may not have the hidden track(s) listed below.  Some of these tracks may be hidden in the pregap, and some hidden simply as a track following the listed tracks.  The list is ordered by artist name using the surname where appropriate. This list contains the names of albums that contain a hidden track and also information on how to find them.  Not all printings of an album contain the same track arrangements, so some copies of a particular album may not have the hidden track(s) listed below.  Some of these tracks may be hidden in the pregap, and some hidden simply as a track following the listed tracks.  The list is ordered by artist name using the surname where appropriate. This list contains the names of albums that contain a hidden track and also information on how to find them.  Not all printings of an album contain the same track arrangements, so some copies of a particular album may not have the hidden track(s) listed below.  Some of these tracks may be hidden in the pregap, and some hidden simply as a track following the listed tracks.  The list is ordered by artist name using the surname where appropriate. This list contains the names of albums that contain a hidden track and also information on how to find them.  Not all printings of an album contain the same track arrangements, so some copies of a particular album may not have the hidden track(s) listed below.  Some of these tracks may be hidden in the pregap, and some hidden simply as a track following the listed tracks.  The list is ordered by artist name using the surname where appropriate. This list contains the names of albums that contain a hidden track and also information on how to find them.  Not all printings of an album contain the same track arrangements, so some copies of a particular album may not have the hidden track(s) listed below.  Some of these tracks may be hidden in the pregap, and some hidden simply as a track following the listed tracks.  The list is ordered by artist name using the surname where appropriate. This list contains the names of albums that contain a hidden track and also information on how to find them.  Not all printings of an album contain the same track arrangements, so some copies of a particular album may not have the hidden track(s) listed below.  Some of these tracks may be hidden in the pregap, and some hidden simply as a track following the listed tracks.  The list is ordered by artist name using the surname where appropriate. This list contains the names of albums that contain a hidden track and also information on how to find them.  Not all printings of an album contain the same track arrangements, so some copies of a particular album may not have the hidden track(s) listed below.  Some of these tracks may be hidden in the pregap, and some hidden simply as a track following the listed tracks.  The list is ordered by artist name using the surname where appropriate. Songs of Innocence is the thirteenth studio album by Irish rock band U2.  Released on 9 September 2014, it was produced by Danger Mouse, with additional production from Paul Epworth, Ryan Tedder, Declan Gaffney, and Flood.  The album was announced at an Apple Inc. product launch event and released the same day to all iTunes Store customers at no cost.  It was exclusive to iTunes, iTunes Radio, and Beats Music until 13 October 2014, when it received a physical release on Island and Interscope Records.  The digital release made the record available to over 500 million iTunes customers, for what Apple CEO Tim Cook marketed as "the largest album release of all time".
Answer: Songs of Innocence