Seizure Disorders USMLE Step 1 Practice Question

A 7-year-old boy is brought to clinic by his mother who reports brief episodes of unresponsiveness occurring 5-10 times daily over the past 3 weeks. During these episodes, lasting approximately 30 seconds, the patient stares blankly, smacks his lips, and makes picking movements at his clothing. Between episodes, he is completely alert and has no postictal confusion. Vital signs are normal. Neurologic examination reveals normal strength, reflexes, and coordination with no focal deficits. Recent developmental screening shows normal age-appropriate skills. An EEG is performed and demonstrates generalized 3-Hz spike-and-wave complexes. Serum glucose, electrolytes, and renal function are all normal. Which of the following is the most appropriate first-line pharmacologic agent for this patient?