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': 'Which of the following has been shown to prolong life in patients with chronic congestive heart failure but has a negative inotropic effect on cardiac contractility? \nSelect and explain. \nA. Carvedilol, B. Digoxin, C. Enalapril, D. Furosemide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]