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: Surgery
[{'content': "Sequence of changes seen in Raynaud's disease is: March 2012 \nSelect and explain. \nA. Red, blue, white, B. White, blue, red, C. Red, blue, white, D. White, red, blue", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans: B i.e. White, blue, red Raynaud's disease is recognized by the characteristic sequence of blanching (constriction of vessels), dusky cyanosis (dilation of capillaries & filling with slowly flowing deoxygenated blood) & red engorgement (relaxation of aerioles & return of oxygenated blood into the dilated capillaries)", 'role': 'assistant'}]