**Core Concept:**
Digoxin is a cardiac glycoside used for the treatment of heart failure and atrial fibrillation. It works by increasing the activity of the sodium-potassium pump in the cardiac muscle cells, leading to decreased sodium and increased potassium uptake, and ultimately increasing the contractility of the heart. When taken in excess, however, it can lead to toxicity due to its narrow therapeutic index.

**Why the Correct Answer is Right:**
Digoxin toxicity is aggravated by the following factors:

* **Option C (Aminoglycoside antibiotics):** Aminoglycoside antibiotics like gentamicin, streptomycin, and amikacin can cause renal tubular toxicity, leading to increased serum digoxin levels due to decreased renal clearance. Combining aminoglycosides with digoxin increases the risk of digoxin toxicity.
* **Option D (Calcium channel blockers):** Calcium channel blockers like verapamil and diltiazem can increase digoxin levels by competitively inhibiting active tubular secretion of digoxin in the kidneys, leading to increased serum digoxin levels and toxicity.
* **Option B (Potassium-sparing diuretics):** Potassium-sparing diuretics like spironolactone, amiloride, and triamterene can increase digoxin levels by inhibiting renal potassium secretion, leading to increased serum digoxin levels and toxicity.

Digoxin toxicity is not aggravated by **Option A (Non-steroidal anti-inflammatory drugs)**, as they do not significantly affect digoxin clearance or binding to plasma proteins, which are the main determinants of digoxin toxicity.

**Why Each Wrong Option is Incorrect:**
1. **Option A (Non-steroidal anti-inflammatory drugs):** Non-steroidal anti-inflammatory drugs (NSAIDs) do not directly affect serum digoxin levels or binding to plasma proteins, which are the main determinants of digoxin toxicity. While NSAIDs can cause renal impairment and increase serum creatinine, this does not directly lead to increased digoxin levels and toxicity.
2. **Option D (Calcium channel blockers):** This option is incorrect because calcium channel blockers do not increase the risk of digoxin toxicity by affecting digoxin binding to plasma proteins or renal clearance. They act on the myocardium and vasculature independently of digoxin's pharmacological effects.
3. **Option B (Potassium-sparing diuretics):** Potassium-sparing diuretics do not directly affect digoxin toxicity by altering its renal clearance or binding to plasma proteins. They primarily affect renal potassium excretion, which is not a direct determinant of digoxin toxicity.
4. **Option C (Aminoglycoside antibiotics):** Aminoglycoside antibiotics can increase digoxin levels by inhibiting renal tubular secretion, but this does not directly increase the risk of digoxin toxicity. The main determinants of digoxin toxicity are renal clearance and binding to plasma proteins, which are not affected by aminoglycoside antibiotics.

**Core Concept:**
Digoxin is a cardiac glycos