The nurse in a primary care provider's office is assessing several patients today. Which patient is most at risk for a stroke?

A. A 92-year-old female who takes warfarin (Coumadin) for atrial fibrillation.
B. A 28-year-old male who uses marijuana after chemotherapy to control nausea.
C. A 42-year-old female who takes oral contraceptives and has migraine headaches.
D. A 72-year-old male who has hypertension and diabetes mellitus and smokes tobacco.