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': "C/F of lateral medullary syndrome -a) Ipsilateral numbness of arm, trunkb) Ipsilateral 12th nerve palsyc) Ipsilateral Horner's syndromed) Contralateral pyramidal tract sign. \nSelect and explain. \nA. ac, B. ad, C. bc, D. cd", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]