A 65-year-old man presents to the emergency room with a severe headache that is diffuse and pounding. He currently takes coumadin (Warfarin) for his atrial fibrillation. The headache began 2 hours ago, and he has no relief with analgesics. On physical exam, he appears confused and there is 5/5 strength in his upper and lower left extremities and 3/5 strength in his right upper and lower extremities. Gait cannot be assessed due to his confusion. Which of the following studies is most widely used for the diagnosis of this patient?A. Non-contrast head computed tomography. Contrast head computed tomography. Magnetic resonance imaging of headD. Lumbar puncture