This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Upper limb, Subject name: Anatomy
[{'content': 'In relation to other metacarpals, the first metacarpal is \nSelect and explain. \nA. Posterior, B. Anterior, C. Laterally rotated, D. Dorsally rotated', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The 1st metacarpal bone (lying on a more anterior plane ) is rotated medially through 90deg relative to other metacarpals. As a result of this rotation , the movements of the thumb take place at right angles to those of other digits. B D Chaurasia 7th edition Page no : 29', 'role': 'assistant'}]