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
First branch of subclavian artery is 
Select and explain. 
A. Internal thoracic artery., B. Thyrocervical trunk., C. Vertebral artery., D. Costocervical trunk.
C: Vertebral artery.
Answer: C: Vertebral artery. 
Explanation: None