**Core Concept**
Potter syndrome is a congenital malformation syndrome resulting from severe fetal renal dysfunction, leading to oligohydramnios and subsequent pulmonary hypoplasia. It is primarily linked to structural abnormalities of the kidneys, such as agenesis or multicystic dysplasia, which disrupt amniotic fluid production.

**Why the Correct Answer is Right**
Potter syndrome is characterized by oligohydramnios due to absent or dysfunctional kidneys. This lack of amniotic fluid leads to lung underdevelopment and other deformities. Bilateral multicystic kidney disease (B) and oligohydramnios (C) are hallmark features. However, **bilateral renal agenesis (A)** is not a feature of Potter syndrome — rather, it is a separate condition (anencephaly or renal agenesis) that may present with oligohydramnios but is not classified under Potter syndrome. The key distinction is that Potter syndrome involves functional renal failure, not complete absence of kidneys.

**Why Each Wrong Option is Incorrect**
Option B: Bilateral multicystic kidney disease is a classic cause of Potter syndrome due to impaired urine production, leading to oligohydramnios.
Option C: Oligohydramnios is a defining feature of Potter syndrome, resulting from renal failure.
Option D: Polyhydramnios is incorrect as it is the opposite of what occurs — Potter syndrome presents with oligohydramnios, not excess amniotic fluid.

**Clinical Pearl / High-Yield Fact**
Remember: **Potter syndrome = oligohydramnios + pulmonary hypoplasia + renal anomaly**. Never confuse it with polyhydramnios — the amniotic fluid is reduced, not increased.

✓ Correct Answer: A. Bilateral renal agenesis