challenge: Which of the following seeded players lost in the first round of the 2009 Monte-Carlo Rolex Masters men's singles tournament?
  
  A. Juan Martín del Potro and Marin Čilić
  B. Janko Tipsarević and Nicolás Lapentti
  C. Gilles Simon and Tommy Robredo
  D. Gaël Monfils and Radek Štěpánek
  Answer: 