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 "Zapata (lithograph)"): Zapata (1932) is a lithograph by the Mexican artist Diego Rivera (1886–1957) that depicts the Mexican revolutionary Emiliano Zapata (1879–1919) as he holds the reins of a horse among a group of "campesinos" (peasants).
Relevant evidence: No