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
Therapeutic level of phenytoin is : 
Select and explain. 
A. 0–9 mg/ml, B. 10–19 mg/ml, C. 20–29 mg/ml, D. 30–39 mg/ ml
B: 10–19 mg/ml
Answer: B: 10–19 mg/ml 
Explanation: None