**Core Concept**
A Zenker diverticulum is a type of esophageal diverticulum that occurs at the cricopharyngeal junction, where the pharynx and esophagus meet. It involves a herniation of the pharyngeal mucosa through a weakness in the muscular wall of the esophagus.

**Why the Correct Answer is Right**
The correct treatment for a Zenker diverticulum is usually surgical or endoscopic, with the goal of alleviating symptoms such as dysphagia and regurgitation. The surgical approach typically involves a cricopharyngeal myotomy, which involves cutting the cricopharyngeal muscle to relieve the obstruction and allow for easier passage of food. This can be performed endoscopically or through an open neck approach.

**Why Each Wrong Option is Incorrect**
* **Option A:** Endoscopic dilation is sometimes used to treat Zenker diverticulum, but it is not considered a definitive treatment and may not provide long-term relief.
* **Option B:** **Barium swallow studies** are often used to diagnose Zenker diverticulum, but they are not a treatment option.
* **Option C:** **Pharyngoplasty** is a surgical procedure that can be used to treat other conditions, such as sleep apnea, but it is not the primary treatment for Zenker diverticulum.

**Clinical Pearl / High-Yield Fact**
It's essential to differentiate between Zenker diverticulum and other types of esophageal diverticula, such as epiphrenic diverticula, which occur lower in the esophagus and may require different treatment approaches.

**Correct Answer: D.** Cricopharyngeal myotomy