**Core Concept**
Edward's syndrome is a genetic disorder caused by a trisomy of chromosome 18. It is characterized by a range of physical and developmental abnormalities. The distinguishing features of Edward's syndrome are critical to identify for accurate diagnosis and management.

**Why the Correct Answer is Right**
The correct answer is associated with the characteristic facial features of Edward's syndrome. Individuals with this condition often have a short nose, low-set ears, and micrognathia. These features are due to the abnormal development of the midface and cranial structures during embryogenesis. The trisomy of chromosome 18 disrupts the normal expression of genes involved in facial development, leading to the characteristic facial features of Edward's syndrome.

**Why Each Wrong Option is Incorrect**
**Option A:** This feature is not a distinguishing characteristic of Edward's syndrome. While some individuals with this condition may have rocker-bottom feet, it is not a unique feature of Edward's syndrome.

**Option B:** This feature is associated with Down syndrome (trisomy 21), not Edward's syndrome. Individuals with Down syndrome often have a flat face, short neck, and protruding tongue.

**Option C:** While some individuals with Edward's syndrome may have heart defects, this is not a distinguishing feature of the condition. Heart defects are a common feature of many genetic disorders and are not unique to Edward's syndrome.

**Clinical Pearl / High-Yield Fact**
A key clinical feature of Edward's syndrome is the presence of rocker-bottom feet, which are due to the abnormal development of the midfoot and forefoot during embryogenesis. This feature is often used as a diagnostic clue for Edward's syndrome.

**Correct Answer: D. Rocker-bottom feet.**