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: Medicine
Which one of the following is the most appropriate clinical tests to confirm the iron-deficiency anaemia? 
Select and explain. 
A. Red blood cell indices, B. Serum ferritin level, C. Bone-marrow examination, D. Urinary iron clearance
B: Serum ferritin level
Answer: B: Serum ferritin level 
Explanation: None