This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen & Pelvis, Subject name: Anatomy
[{'content': 'Rotation of the stomach during development results in movement of the left vagus nerve from its original position. Through approximately how many degrees of rotation does the nerve move, and what is its final position? \nSelect and explain. \nA. 90deg to become the anterior vagal trunk, B. 90deg to become the posterior vagal trunk, C. 270deg to become the anterior vagal trunk, D. 270deg to become the posterior vagal trunk', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Rotation of the gut tube is a major event in the development of the gastrointestinal system. Parts of the tube rotate 270deg, but the proximal foregut, specifically that portion that forms the esophagus, rotates only 90deg. Looking from below (the standard CT or MRI view), this rotation is counterclockwise. This brings the left vagus nerve onto the anterior surface of the esophagus as it passes through the thorax.', 'role': 'assistant'}]