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: Anatomy
[{'content': 'Attachment to the first rib is all Except \nSelect and explain. \nA. Scalenius-anterior, B. Scalenius-posterior, C. Scalenius-medius, D. Suprapleural membrane', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B. i.e. Scalenius posterior', 'role': 'assistant'}]