Task: Explanation
Input (English): By the People, for the People is a compilation album by American heavy metal band Mudvayne. It was released on November 27, 2007 by Epic Records. The album features a track listing chosen entirely by the band's fans, with the band determining which version appears on the record (e.g. live, demo, acoustic), as well as two new songs, "Dull Boy" and a cover of The Police's song "King of Pain" (both produced by Dave Fortman). If the album was pre-ordered through the Sony Music Store, it was packaged with a free lithograph of the lyrics to "Dull Boy", signed and numbered by Mudvayne vocalist Chad Gray. If it was ordered after the disc was released, the lithograph was shipped approximately three weeks later and was neither signed nor numbered. Question: On which group is this artist, who signed and numbered the lithograph for the pre-ordered album "By the People, for the People," currently a vocalist? Answer: Hellyeah
Output (English):  If the album was preordered through the Sony Music Store, it was packaged with a free lithograph of the lyrics to Dull Boy, signed and numbered by Mudvayne vocalist Chad Gray.