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: Pharmacology
[{'content': 'Patients taking a β–adrenergic receptor blocking drug may experience all of the following except: \nSelect and explain. \nA. Exacerbation of existing heart block, B. Precipitation of heart failure, C. Nasal blockage, D. Cold extremities', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]