challenge: Where was the meeting held that led to the formation of the Commercial Spaceflight Federation, then known as the Personal Spaceflight Federation?
  
  A. Virgin Galactic's headquarters in Mojave, California
  B. The National Space Foundation's headquarters in Washington D.C.
  C. The X Prize Foundation's headquarters in New York City
  D. SpaceX's headquarters in El Segundo, California
  Answer: 