A 65-year-old woman with heart failure and reduced ejection fraction (HFrEF, EF 35%) presents to clinic for follow-up. Current medications include lisinopril 10 mg daily, metoprolol succinate 47.5 mg daily, and furosemide 40 mg daily. Her symptoms have been stable on this regimen for 6 months. To further optimize her therapy, sacubitril/valsartan is initiated at a standard starting dose. Two days later, she reports a persistent dry cough and mild dyspnea on exertion. Vital signs: BP 108/62 mmHg, HR 78 bpm, RR 20/min, SpO2 98% on room air. Labs: K+ 5.4 mEq/L (previously 4.8), Cr 1.1 mg/dL (baseline 1.0). Physical exam shows no orthopnea, jugular venous pressure normal, and clear lung fields. Which of the following best explains her clinical deterioration?

1. A)Sacubitril competitively inhibits neprilysin at the glomerulus, reducing urinary potassium excretion and causing hyperkalemia-induced cough reflex
2. B)Valsartan's angiotensin II receptor blockade causes direct airway smooth muscle contraction, independent of ACE inhibitor effects
3. C)Concurrent use of lisinopril and sacubitril/valsartan results in excessive RAAS inhibition; the cough is attributable to lisinopril-induced accumulation of bradykinin and substance P in the respiratory tractGABARITO
4. D)Metoprolol enhances the bioavailability of sacubitril, causing toxic accumulation and direct lung parenchymal inflammation
5. E)Furosemide-induced hypokalemia has been masked by initiation of dual RAAS inhibitors, and the cough is a compensatory response to intracellular potassium shifts