premise: Hearts of Stone is the fifth studio album by American rock band Stoneground, released in 1978 on Warner Bros. Produced by Bob Gaudio, it marked Stoneground's return to a major label, having released their previous album, "Flat Out" (1976), on their own label. "Prove It" was released as the first single from "Hearts of Stone".
hypothesis: Stoneground released their first studio album in 1970 
reason: The context says that Stoneground released 5 studio albums, with the 4th and 5th coming out in 1976 and 1978, respectively. It does not say when their first studio album came out, so it is feasible it was released in 1970. There is no way of knowing. The computer probably assumed the statement was wrong because it does not understand this progression of logic. 