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': 'Which of this part of vertebral canal will show secondary curves with concavity backwards? \nSelect and explain. \nA. Cervical, B. Thoracic, C. Sacral, D. Coccyx', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Primary curvatures (concavity forwards) → thoracic and sacral.\nSecondary curvatures (concavity backwards) → cervical and lumbar.', 'role': 'assistant'}]