**Core Concept**
Intermittent dysphagia is a symptom characterized by periodic difficulty in swallowing, which can be caused by various esophageal disorders. The underlying pathophysiology involves abnormal esophageal motility or mechanical obstruction.

**Why the Correct Answer is Right**
Achalasia cardia is a primary motility disorder of the esophagus, where there is a failure of the lower esophageal sphincter (LES) to relax, resulting in intermittent dysphagia, regurgitation, and difficulty in swallowing. This condition is often associated with degeneration of the myenteric plexus, leading to impaired peristalsis and abnormal esophageal contractions.

**Why Each Wrong Option is Incorrect**
**Option A:** Stricture is a mechanical obstruction of the esophagus, typically caused by chronic inflammation or scarring, resulting in persistent dysphagia, not intermittent dysphagia.
**Option B:** Reflux esophagitis is an inflammatory condition of the esophagus, caused by gastroesophageal reflux disease (GERD), which may cause intermittent dysphagia, but it is not the primary cause.
**Option D:** Pharyngeal diverticulum is an outpouching of the pharyngeal mucosa, which can cause intermittent dysphagia, but it is a mechanical obstruction, not a motility disorder.
**Option E:** Diffuse esophageal spasm is a condition characterized by abnormal, simultaneous contractions of the esophagus, which can cause intermittent dysphagia, but it is not as common as achalasia cardia.

**Clinical Pearl / High-Yield Fact**
Achalasia cardia is often associated with a characteristic "bird's beak" appearance on barium swallow studies, which is a result of the failure of the LES to relax and the accumulation of food in the esophagus.

**Correct Answer:** C. Achalasia cardia