question: Q:A 73-year-old man presents to his primary care physician with chest pain. He noticed the pain after walking several blocks, and the pain is relieved by sitting. On exam, he has a BP 155/89 mmHg, HR 79 bpm, and T 98.9 F. The physician refers the patient to a cardiologist and offers prescriptions for carvedilol and nitroglycerin. Which of the following describes the mechanism or effects of each of these medications, respectively?? 
  {'A': 'Increased cAMP; Increased cAMP', 'B': 'Increased contractility; Decreased endothelial nitrous oxide', 'C': 'Decreased cAMP; Increased cGMP', 'D': 'Decreased cGMP; Increased venous resistance', 'E': 'Increased heart rate; Decreased arterial resistance'},