challenge: What are two notable roles played by Jennifer Crystal Foley?
  
  A. Christie Parker in Friends and Rachel Green on How I Met Your Mother
  B. Christie Parker in Once and Again and Rachel Taub on House
  C. Phoebe Buffay in Once and Again and Monica Geller on House
  D. Joey Tribbiani in Once and Again and Chandler Bing on House
  Answer: 