This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
The Antiepileptic drug, Phenytoin therapeutic blood level is 
Select and explain. 
A. 0-9 mcg/ml, B. 10-19 mcg/ml, C. 20-29 mcg/ml, D. 30-39 mcg/ml
B: 10-19 mcg/ml
Answer: B: 10-19 mcg/ml 
Explanation: (B) 10-19 mcg/ml# SERUM PHENYTOIN LEVELS:> Therapeutic range is 10-20 mcg/mL.# Total phenytoin levels (mcg/mL) - Typical corresponding Signs & Symptoms: Lower than 10- Rare Between 10 and 20 - Occasional mild nystagmus Between 20 and 30 - Nystagmus Between 30 and 40 - Ataxia, slurred speech, nausea, and vomiting Between 40 and 50 - Lethargy and confusion Higher than 50 - Coma and seizures