**Core Concept**
The term "stepping" in a clinical context refers to the movement of the diaphragm during respiration, specifically the upward movement of the diaphragm as it contracts and descends into the thoracic cavity.

**Why the Correct Answer is Right**
During inspiration, the diaphragm contracts and flattens, increasing the volume of the thoracic cavity. This contraction, also known as "stepping," allows the lungs to expand and draw in air. The diaphragm's upward movement is facilitated by the relaxation of the abdominal muscles and the elastic recoil of the lungs. As the diaphragm descends, it increases the negative intrathoracic pressure, drawing air into the lungs through the trachea.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because stepping is not associated with the movement of the rib cage during respiration.
* **Option B:** This option is incorrect because stepping is not a term used to describe the movement of the abdominal muscles during inspiration.
* **Option C:** This option is incorrect because stepping is not a term used to describe the movement of the intercostal muscles during respiration.

**Clinical Pearl / High-Yield Fact**
The diaphragm is the primary muscle responsible for respiration, accounting for approximately 75% of the total respiratory effort.

**Correct Answer:** C.