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?
Sentence (from "By the People, for the People"): 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.
Relevant evidence: Yes