This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Rate of iron uptake is regulated by which one of the following : 
Select and explain. 
A. Mucosal cell iron stores, B. Route of administration, C. Preparation administered, D. Age of the patient
A: Mucosal cell iron stores
Answer: A: Mucosal cell iron stores 
Explanation: None