Answer
Four is the correct answer. Ernst Happel is one of only six managers to have won league titles in at least four different countries. He achieved this remarkable feat by leading Feyenoord (Netherlands), Club Brugge (Belgium), Hamburger SV (Germany), and FC Tirol Innsbruck (Austria) to league championships. Happel's success across multiple countries is a testament to his tactical acumen and ability to adapt to different playing styles and cultures.