**Core Concept**
The diaphragm is a dome-shaped muscle that separates the chest cavity from the abdominal cavity, playing a crucial role in respiration. Its anatomy is essential for understanding breathing mechanics and thoracic cavity dynamics.

**Why the Correct Answer is Right**
The diaphragm is a dome-shaped muscle with the right side being lower than the left side due to the presence of the liver. The liver, a large abdominal organ, is located primarily on the right side of the abdominal cavity, pushing the right diaphragmatic crus downward. This anatomical arrangement allows for more space in the thoracic cavity on the right side, facilitating breathing. The diaphragm's dome shape enables it to expand and contract, increasing and decreasing the volume of the thoracic cavity, which in turn affects lung expansion and air entry.

**Why Each Wrong Option is Incorrect**
**Option A:** The heart, located in the mediastinum, does not push down the diaphragm. Instead, the pericardial sac surrounding the heart allows for some movement while maintaining its position within the thoracic cavity.
**Option B:** The diaphragm is not lower on the left side than on the right side. The liver's presence on the right side causes the right diaphragm to be lower, not the left.
**Option D:** Diaphragmatic hernias can occur on either side, but they are more common on the left side due to the presence of the pericardial sac and the aorta on the right. The left side's relative lack of pressure from surrounding organs makes it a more common site for hernias.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the shape and position of the diaphragm are influenced by the surrounding organs, particularly the liver and the heart. Understanding these anatomical relationships is essential for diagnosing and managing respiratory and thoracic conditions.

**✓ Correct Answer: C. Right side lower than left side**