This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Medicine
[{'content': 'Features of parkinsons disease- \nSelect and explain. \nA. Decreased Blinking, B. Rigidity, C. On-off phenomenon, D. Objective (downside arrow) muscle power', 'role': 'user'}, {'content': "Answer: B \nExplanation: Rigidity is seen in Parkinson's disease. Two types : 1) Cogwheel type, mostly upper limbs(due to tremor superimposed on rigidity) 2) Lead pipe rigidity Rigidity causes stiffness and flexed posture. Ref Harrison20th edition pg 1567", 'role': 'assistant'}]