Problem: An older adult female patient with a history of atrial fibrillation presents to the emergency department with sudden onset of right-sided weakness and difficulty speaking. Imaging reveals a focal ischemic stroke. On further examination, an echocardiogram shows a thrombus in the left atrium. Based on this clinical presentation and findings, which type of stroke is most likely? Group of answer choices Hemorrhagic stroke Lacunar stroke Thrombotic stroke Embolic stroke