Final answer:
The nurse should contact the provider to request potassium supplements to minimize the risk of digoxin toxicity.
Step-by-step explanation:
When a patient is taking a thiazide diuretic and quinidine, the addition of digoxin can increase the risk of digoxin toxicity. Thiazide diuretics can cause hypokalemia (low potassium levels), which can increase the cardiac toxicity of digoxin. Therefore, the nurse should contact the provider to request potassium supplements (option d) to maintain appropriate potassium levels and minimize the risk of digoxin toxicity.