This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous system, 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: Phenytoin therapeutic plasma concentration is 10-20 mg/ml. Ref: K D Tripati 7th edition Page no 422. Table 30.2