user: Question: Which European Cup is in the 1990-91 season?
Columns: ['Season', 'Club', 'National League', 'National Cup', 'European Cup']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['1964-65', 'Real Madrid', 'Spanish National League', "Spanish Generalísimo's Cup", "FIBA European Champion's Cup"]
SQL:

assistant: SELECT "European Cup" FROM "Table" WHERE "Season" = '1990-91';