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: Medicine
[{'content': 'Hemiballismus is due to lesion in \nSelect and explain. \nA. Ipisilateral caudate nucleus, B. Contralateral sub-thalamic lesion, C. Contralateral putamen, D. Ipsilateral sub-thalamic lesion', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Answer- B. Contralateral sub-thalamic lesionSub-thalamic nucleus- Contralateral hemiballismus', 'role': 'assistant'}]