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: Pathology
[{'content': "Raynaud's phenomenon what change is seen in vessels initial stage - \nSelect and explain. \nA. No change (Fibrinoid, Thrombosis), B. Thrombosis, C. Fibrinoid necrosis, D. Hyaline sclerosis", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Structural changes in the arterial walls are absent except late in the course, when intimal thickening can appear.', 'role': 'assistant'}]