**Core Concept**
Peristalsis is the rhythmic, wave-like movement of the gastrointestinal tract that propels food, fluid, and gas through the digestive system. This process involves the coordinated contraction and relaxation of smooth muscle cells in the gastrointestinal tract wall. The enteric nervous system plays a crucial role in regulating peristalsis.

**Why the Correct Answer is Right**
The correct answer involves identifying the component that is not directly involved in the peristalsis process. The enteric nervous system, consisting of the myenteric and submucosal plexuses, releases neurotransmitters such as acetylcholine, which stimulate the contraction of smooth muscle cells, thereby facilitating peristalsis. Other components involved in peristalsis include:

* **Option A:** The interstitial cells of Cajal, which act as pacemakers to generate the rhythmic electrical activity that drives peristalsis.
* **Option C:** The smooth muscle cells, which contract and relax in a coordinated manner to propel contents through the digestive system.

**Why Each Wrong Option is Incorrect**
* **Option B:** The submucosal plexus is not directly involved in peristalsis; it primarily regulates the secretion of digestive enzymes and the absorption of nutrients.

**Clinical Pearl / High-Yield Fact**
The enteric nervous system can function independently of the central nervous system, often referred to as the "little brain" of the gut.

**Correct Answer: B. The submucosal plexus.**