This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
The drug used in absence seizures and having a narrow spectrum of antiepileptic activity is: 
Select and explain. 
A. Lamotrigine, B. Ethosuximide, C. Sodium valproate, D. Primidone
B: Ethosuximide
Answer: B: Ethosuximide 
Explanation: (Ref: KDT 6/e p406, 407) Ethosuximide is useful only in the treatment of absence seizures (petit mal epilepsy). Valproic acid and lamotrigine are broad spectrum antiepileptic drugs.