A 45-year-old man has had poorly controlled hypertension ranging from 150/90 mm Hg to 160/95 mm Hg for the past 11 years. Over the past 3 months, his blood pressure has increased to 250/125 mm Hg. On physical examination, his temperature is 36.9deg C. His lungs are clear on auscultation, and his heart rate is regular. There is no abdominal pain on palpation. A chest radiograph shows a prominent border on the left side of the heart. Laboratory studies show that his serum creatinine level has increased during this time from 1.7 mg/dL to 3.8 mg/dL. Which of the following vascular lesions is most likely to be found in this patient's kidneys?