**Core Concept**
The non-progressive contraction of the esophagus is a type of peristalsis that helps propel food bolus towards the stomach. This type of contraction is characterized by simultaneous contraction and relaxation of esophageal muscles, resulting in a non-propulsive wave.

**Why the Correct Answer is Right**
The correct answer is associated with primary peristalsis, which is the primary mechanism of esophageal propulsion. Primary peristalsis is initiated by swallowing and is responsible for the initial movement of the food bolus through the esophagus. The simultaneous contraction and relaxation of esophageal muscles in primary peristalsis result in a non-propulsive wave, which helps to mix food with saliva and mucus, and also helps to prevent over-distension of the esophagus.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because primary peristalsis is the correct answer. Secondary peristalsis is associated with progressive contraction of the esophagus.
* **Option B:** This option is incorrect because tertiary peristalsis is associated with the clearance of remaining food residue in the esophagus after a meal, not non-progressive contraction.
* **Option D:** This option is incorrect because it is not a recognized type of peristalsis.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that primary peristalsis is the primary mechanism of esophageal propulsion, and it is characterized by non-progressive contraction of the esophagus.

**Correct Answer: C. Primary peristalsis.**