This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pericardial Disease, Subject name: Medicine
[{'content': 'In case of chest pain with pericarditis and pericardial effusion, pain is refered by? \nSelect and explain. \nA. Phrenic nerve, B. Vagus nerve, C. Trigeminal nerve, D. None', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. (a) Phrenic nerveRef: Cunningham's textbook of anatomy by Daniel john Cunningham p 699, 700, Gray's anatomy 39/e, p 996", 'role': 'assistant'}]