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: Physiology
Which of the following variables is measured on the ordinal scale 
Select and explain. 
A. Type of anemia, B. Severity of anemia, C. Hemoglobin level, D. Serum ferritin level
B: Severity of anemia
Answer: B: Severity of anemia 
Explanation: None