challenge: What is the key difference in appearance between Papilio nobicea and Papilio zenobia?
  
  A. Papilio nobicea has more colorful patterns than Papilio zenobia
  B. Papilio nobicea has pure white discal bands, while Papilio zenobia has a cream tinge
  C. Papilio nobicea has larger wings than Papilio zenobia
  D. Papilio nobicea has cream-colored discal bands, while Papilio zenobia has white discal bands
  Answer: 