This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
All of the following helps in maturation of rbc except 
Select and explain. 
A. Castles intrinsic factor, B. Iron, C. Vit b12, D. Folic acid
A: Castles intrinsic factor
Answer: A: Castles intrinsic factor 
Explanation: Castle's intrinsic factor hepls in b12 absorption