challenge: Which of the following accurately describes the rhoptry neck and bulb regions?
  
  A. The rhoptry neck contains RONs, and the rhoptry bulb contains ROPs and membranous materials.
  B. The rhoptry neck contains ROPs while the rhoptry bulb contains RONs.
  C. The rhoptry neck is electron-lucent, and the rhoptry bulb is electron-dense.
  D. The rhoptry neck is a larger, bulbous base, and the rhoptry bulb is an electron-dense duct.
  Answer: 