**Core Concept**
Right-sided heart failure occurs when the right ventricle is unable to pump blood effectively, often leading to fluid accumulation in the body. This condition is characterized by various clinical manifestations, including peripheral edema, ascites, and hepatomegaly. In contrast, left-sided heart failure typically presents with pulmonary edema.

**Why the Correct Answer is Right**
Pulmonary edema is a hallmark of left-sided heart failure, not right-sided heart failure. This is because the left ventricle pumps blood into the pulmonary circulation, and when it fails, fluid accumulates in the lungs, causing pulmonary edema. In right-sided heart failure, the increased pressure in the right atrium and ventricle leads to fluid accumulation in the peripheral veins, causing peripheral edema, ascites, and hepatomegaly.

**Why Each Wrong Option is Incorrect**
**Option B:** Ascites is a common manifestation of right-sided heart failure, as the increased pressure in the right atrium and ventricle leads to fluid accumulation in the abdominal cavity.
**Option C:** Oliguria, or decreased urine output, can occur in both left- and right-sided heart failure due to decreased cardiac output and renal perfusion.
**Option D:** Dependent edema is a characteristic of right-sided heart failure, as the increased pressure in the peripheral veins leads to fluid accumulation in the dependent areas of the body.

**Clinical Pearl / High-Yield Fact**
In pediatrics, right-sided heart failure often presents with signs of peripheral edema, ascites, and hepatomegaly, whereas left-sided heart failure typically presents with respiratory distress and pulmonary edema.

✓ Correct Answer: A. Pulmonary oedema