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': 'Concerning brachial plexus, which of the following facts are true \nSelect and explain. \nA. Formed by spinal nerve C5- C8 and T1, B. Most common site of injury is upper trunk, C. Injury may occur, during breech delivery, D. Radial nerve is branch of medial cord', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Brachial plexus is formed by the anterior primary rami of spinal nerves C5-C8 and T1, with contribution from the anterior primary rami of C4 and T2. Radial nerve is a branch of posterior cord. Injury to the upper trunk causes Erb&;s paralysis. B D Chaurasia 7th edition Page no: 58', 'role': 'assistant'}]