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: Radiology
[{'content': 'Beheaded Scottish terrier sign is? \nSelect and explain. \nA. Spondylosis, B. Spondylolisthesis, C. Lumbar canal stenosis, D. Slipped Disc', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Spondylolisthesis', 'role': 'assistant'}]