**Core Concept**
Congestive heart failure (CHF) is a condition where the heart is unable to pump enough blood to meet the body's needs, leading to fluid buildup in the lungs and other parts of the body. Managing CHF requires careful consideration of medications that can exacerbate or improve the condition.

**Why the Correct Answer is Right**
Digoxin is a cardiac glycoside that increases the force of cardiac contractions and slows the heart rate, which can improve cardiac output in patients with CHF. It works by inhibiting the sodium-potassium ATPase pump, leading to an increase in intracellular calcium levels and enhanced contractility. Digoxin is also a vasodilator, which can help reduce peripheral resistance and improve cardiac output.

**Why Each Wrong Option is Incorrect**
* **Option A:** Furosemide is a loop diuretic that can be used to manage CHF by reducing fluid buildup in the lungs and other parts of the body. However, it can also lead to hypokalemia, which can worsen CHF.
* **Option B:** Nitrates are vasodilators that can be used to manage CHF by reducing preload and afterload. However, they can also lead to hypotension and worsen cardiac output.
* **Option C:** Beta-blockers are typically contraindicated in CHF due to their negative inotropic effects, which can worsen cardiac output.

**Clinical Pearl / High-Yield Fact**
Be cautious when using diuretics in CHF patients, as they can lead to hypokalemia, which can worsen the condition.

**Correct Answer: D. Digoxin**