Question: The 2015 Clemson Tigers football team represented Clemson University in the 2015 NCAA Division I FBS football season, ranked No. 1 throughout the College Football Playoff (CFP) rankings, Clemson defeated which team for No. 4, which football team that represented the University of Oklahoma in the 2015 NCAA Division I FBS football season, the 121st season of Sooner football?
Sentence (from "2015 Clemson Tigers football team"): They played their home games at Memorial Stadium, also known as "Death Valley."
Relevant evidence: No