A 69-year-old man is brought to the emergency department after falling and striking his head on the floor about 1 hour ago. His daughter reports a brief loss of consciousness at the time of the fall, followed by persistent, severe headache and marked nausea. The patient takes warfarin for a cardiac condition. Vital signs are within normal limits. Neurologic examination reveals no focal motor or sensory deficits, but the patient is noticeably confused and has difficulty appropriately answering questions. A non-contrast CT scan of the head is shown in Figure A. What is the most likely explanation for this patient’s current symptoms?