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: Anaesthesia
[{'content': 'A successful stellate ganglion block can produce – \nSelect and explain. \nA. Hypotension, B. Horner syndrome, C. Brachial plexus involvement, D. Hemifacial anaesthesia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]