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 "2014 Clemson Tigers football team"): The Tigers were led by head coach Dabo Swinney in his sixth full year and seventh overall since taking over midway through 2008 season.
Relevant evidence: No