Question: During what season of Europe's secondary club football tournament was the  2017 UEFA Europa League Final, where Manchester United finished in sixth place?
Sentence (from "2017 UEFA Europa League Final"): With this victory, they joined Juventus, Ajax, Bayern Munich and Chelsea as the only clubs to have won all three major European trophies (European Champion Clubs' Cup/UEFA Champions League, UEFA Cup/Europa League, and the now defunct UEFA Cup Winners' Cup).
Relevant evidence: No