challenge: What is the origin of the name 'Joachimsthaler' coins?
  
  A. They were named after the king who introduced them
  B. They were named after a German word for 'mountain'
  C. They were named after the town where they were minted, which was named after Saint Joachim and the German word for 'valley'
  D. They were named after the metal they were made of
  Answer: 