challenge: What is a key distinguishing feature of Ambulyx staudingeri compared to Ambulyx pryeri?
  
  A. The presence of a dark tornal shade on the hindwing
  B. The posterior third of the forewing upperside subterminal line is closer to the termen
  C. The coloration of the body is entirely green
  D. The absence of a subterminal line on the forewing
  Answer: 