A 42-year-old woman with a 10-year history of migraine with aura presents to the emergency department with acute-onset left-sided hemiparesis and dysarthria. Vital signs include BP 168/98 mmHg, HR 92/min, and temperature 37.2°C. She denies smoking, recent trauma, or neck pain. MRI brain demonstrates acute ischemic infarction in the right middle cerebral artery territory. Noncontrast CT of the head rules out hemorrhage. She is otherwise healthy with no history of hypertension, atrial fibrillation, or prior stroke. Laboratory studies show normal complete blood count, basic metabolic panel, and coagulation profile. Which of the following is the most likely explanation for her acute ischemic stroke?

1. A)Cardioembolic stroke secondary to paroxysmal atrial fibrillation
2. B)Acute atherosclerotic plaque rupture with in situ thrombosis
3. C)Arterial dissection of the right internal carotid arteryGABARITO
4. D)Paradoxical embolism through a patent foramen ovale
5. E)Hypercoagulable state from occult malignancy