This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc. (R.B.C), Subject name: Pathology
RBC contains? 
Select and explain. 
A. Iron, B. Folic acid, C. Vitamin C, D. Biotin
A: Iron
Answer: A: Iron 
Explanation: Ans. (a) IronRef: Robbings pathology 9th ed. /631, 649