This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood Vessels, Subject name: Pathology
[{'content': "Raynaud's phenomenon what change is seen in vessels initial stage: \nSelect and explain. \nA. No change, B. Thrombosis, C. Fibrinoid necrosis, D. Hyaline sclerosis", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. (a) No change(Ref: Harrison 17th ed Table 243-1)Most common cause of Raynaud's Phenomenon -Primary or idiopathic.In initial stages of Raynaud's phenomenon no changes is seen late stages may show atherosclerosis or thrombosis", 'role': 'assistant'}]