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: Physiology
[{'content': 'Appreciation of shape and size of an object placed in the hand is lost in the lesion of: \nSelect and explain. \nA. Tractus gracilis, B. Tractus cuneatus, C. Lateral spinothalamic tract, D. Spino-reticular tract', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Tractus cuneatus', 'role': 'assistant'}]