A nurse is caring for a client who is taking digoxin to treat heart failure. Which of the following factors predisposes this client to developing digoxin toxicity?

A. Taking a high-ceiling diuretic, such as furosemide, can lead to hypokalemia (low potassium levels), which increases the risk of digoxin toxicity. Low potassium levels enhance the effects of digoxin on the heart, making toxicity more likely. B. Taking an HMG-CoA reductase inhibitor (statin) is not directly related to digoxin toxicity. Statins are used to lower cholesterol levels and do not significantly interact with digoxin. C. Having a 10-year history of COPD does not predispose a client to digoxin toxicity. COPD affects the respiratory system and is not directly related to digoxin metabolism or excretion. D. Having a prolapsed mitral valve is a cardiac condition but does not specifically increase the risk of digoxin toxicity. The primary concern with digoxin toxicity is electrolyte imbalances, particularly potassium levels.