challenge: What type of films does the Northrop Grumman IMAX Theatre at Clark Planetarium feature?
  
  A. Both 3-D and 2-D films, with a focus on science and nature documentary programming
  B. Only 2-D films
  C. Only 3-D films
  D. Both 3-D and 2-D films, with a focus on action movies
  Answer: 