**Core Concept**
Intermittent dysphagia refers to the episodic difficulty in swallowing, often resulting from mechanical obstruction or transient neurological dysfunction affecting the oropharyngeal or esophageal phase of deglutition.

**Why the Correct Answer is Right**
The correct answer is related to the **achalasia**, a motility disorder characterized by the failure of the lower esophageal sphincter (LES) to relax, leading to intermittent dysphagia, regurgitation, and weight loss. This condition arises from the degeneration of the myenteric plexus in the esophagus, disrupting the normal coordination between esophageal peristalsis and LES relaxation. The pathophysiology involves the absence of the inhibitory neurotransmitter nitric oxide (NO) in the esophageal smooth muscle, which normally promotes relaxation of the LES.

**Why Each Wrong Option is Incorrect**
**Option A:** Zenker's diverticulum is a false diverticulum that occurs in the upper esophagus, typically presenting with dysphagia, regurgitation of undigested food, and occasionally aspiration pneumonia. It is not associated with intermittent dysphagia.
**Option B:** Esophageal stricture is a narrowing of the esophageal lumen due to chronic inflammation, usually resulting from gastroesophageal reflux disease (GERD), which causes progressive dysphagia that worsens over time.
**Option C:** Gastroesophageal reflux disease (GERD) may present with intermittent dysphagia, but it is more commonly associated with heartburn, regurgitation, and chest pain.

**Clinical Pearl / High-Yield Fact**
Achalasia is a rare condition, accounting for approximately 1 in 100,000 cases of dysphagia, and its diagnosis often requires a combination of clinical evaluation, upper GI series, esophageal manometry, and endoscopy.

**Correct Answer: C. Esophageal stricture is a narrowing of the esophageal lumen due to chronic inflammation, usually resulting from gastroesophageal reflux disease (GERD), which causes progressive dysphagia that worsens over time.**