challenge: What is the primary reason for the energetic favorability of Beryllium-8's decay into two alpha particles?
  
  A. The doubly magic configuration of the Beryllium-8 nucleus
  B. The total energy of Beryllium-8 being greater than that of two alpha particles
  C. The low energy of the Coulomb barrier between the alpha particles
  D. The high binding energy per nucleon of Beryllium-8
  Answer: 