The return of former player George Graham as manager in 1986 brought a third period of glory. Arsenal won the League Cup in 1987, Graham's first season in charge. This was followed by a League title win in 1988–89, won with a last-minute goal in the final game of the season against fellow title challengers Liverpool. Graham's Arsenal won another title in 1990–91, losing only one match, won the FA Cup and League Cup double in 1993, and a second European trophy, the European Cup Winners' Cup, in 1994. Graham's reputation was tarnished when he was found to have taken kickbacks from agent Rune Hauge for signing certain players, and he was dismissed in 1995. His replacement, Bruce Rioch, lasted for only one season, leaving the club after a dispute with the board of directors.
Who did Arsenal beat for their 1990-91 title? (If the question is unanswerable, say "unanswerable")
unanswerable