Brain-teaser Monday.

The UEFA Champions League has reached the quarter finals stage. In honor, today's teaser is football related.

Corporate shirt sponsorship is a huge part of European football with the back room deal-making almost as dramatic as the on-field action. Major brands, like Siemens, Carlsberg, T-Mobile and Deutsche Bank willingly fork out tens of millions of dollars to have their names and logos adorn the distinct jerseys of the major teams in England, Italy, Spain, Germany as well as the other European football leagues.

For instance, Samsung paid Chelsea F.C. 50 million pounds for the honor. Recently, it cost Emirates Airlines over 70 million dollars to have their name front and center on the famous red and black jerseys of A.C. Milan. And it's not just well-known brands that are paying to play. Tamoil, a Libyian-based oil company signed a hundred million plus euro deal with Juventus F.C. for the exclusive rights to the black and white shirt of the club from Turin.

That said, there is one European football club that has NEVER accepted corporate sponsorship since it's founding back in the late nineteenth century. Which is the legendary club that refuses to sell out its jersey?

• A.F.C. Ajax
• Arsenal F.C.
• A.S. Roma
• B.V Borussia Dortmund  
• F.C. Barcelona
• F.C. Bayern Munich
• F.C. Dynamo Kiev
• F.C. Internazionale Milano
• F.C. Porto 
• F.C. Zenit Saint Petersbug
• Liverpool F.C.
• Manchester United F.C.
• M.K. Dons
• Olympique de Marseilles
• Olympique Lyonnais
• P.S.V. Eindhoven
• Real Madrid C.F.
• R.S.C. Anderlecht
• S.S.C. Napoli 
• S.L. Benfica
• Valencia C.F.

Answer to last week's brain teaser: 4 years ago