Premise: Black Sabbath were an English rock band , formed in Birmingham in 1968 , by guitarist and main songwriter Tony Iommi , bassist and main lyricist Geezer Butler , singer Ozzy Osbourne , and drummer Bill Ward . Black Sabbath are often cited as pioneers of heavy metal music . Heavy metal ( or simply metal ) is a genre of rock music that developed in the late 1960s and early 1970s , largely in the United Kingdom and the United States .
Hypothesis: Black Sabbath are often cited as pioneers of a genre of rock music that developed in the late 1960s and early 1970s.
Label: ENTAILMENT