Final answer:
The molecule formed from the breakdown of protoporphyrin within macrophages that have consumed RBCs is unconjugated bilirubin (option 4).
Step-by-step explanation:
When macrophages consume red blood cells (RBCs), the protoporphyrin within the heme is broken down into unconjugated bilirubin. In this process, the non-iron portion of heme degrades into biliverdin and subsequently into bilirubin, which is then transported by albumin to the liver to be used in bile production.
The molecule in question, which is formed when macrophages that have phagocytized RBCs break down the protoporphyrin from heme, is unconjugated bilirubin. Therefore, the correct answer to the student's question is 4) Unconjugated bilirubin.