challenge: What was the result of the merger between Vilppula and Mänttä on 1 January 2009?
  
  A. Mänttä and Vilppula formed the municipality of Mänttä-Vilppula
  B. Vilppula remained an independent municipality
  C. Vilppula became a part of the municipality of Keuruu
  D. Mänttä became a part of the municipality of Jyväskylä
  Answer: 