challenge: What was released on October 9, 2012, by Warner Home Video?
  
  A. A combo pack featuring a DVD and digital download of Big Top Scooby-Doo!
  B. A combo pack featuring a Blu-ray and UltraViolet of Big Top Scooby-Doo!
  C. A combo pack featuring a Blu-ray, DVD, UltraViolet and digital download of Big Top Scooby-Doo!
  D. A single-disc Blu-ray of Big Top Scooby-Doo!
  Answer: 