This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Peripheral aerial disease can be treated by all, EXCEPT: \nSelect and explain. \nA. Pentoxifylline, B. Cilostazol, C. Sildenafil, D. Percutaneous angioplasty', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Pentoxifylline, a xanthine derivative, is thought to act by reducing the viscosity of blood, allowing it to flow more easily through paially obstructed areas. Cilostazol, a phosphodiesterase type 3 (PDE3) inhibitor, is poorly understood, but may have selective antiplatelet and vasodilating effects. Both drugs have been shown to increase exercise tolerance in patients with severe claudication. Percutaneous angioplasty with stenting is often effective in patients with medically intractable signs and symptoms of ischemia. Ref: Katzung, 11th edition, Chapter 12.', 'role': 'assistant'}]