**Core Concept**
Barrett's esophagus is a metaplastic change in the esophageal mucosa, characterized by the replacement of normal squamous epithelium with columnar epithelium, often as a result of chronic gastroesophageal reflux disease (GERD). Endoscopic mucosal resection (EMR) is a procedure used to remove early cancerous or precancerous lesions within the esophagus.

**Why the Correct Answer is Right**
EMR involves the removal of the mucosal layer of the esophagus, which in the case of Barrett's esophagus, contains dysplastic or cancerous cells. This procedure is particularly useful for removing high-grade dysplasia or intramucosal carcinoma, thereby preventing the progression to invasive cancer. The removal of the mucosa also allows for the assessment of the underlying muscularis mucosae, which can help in the diagnosis of invasive cancer.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because EMR does not remove the muscularis mucosae, which is the layer beneath the mucosa that contains the submucosal plexus of the enteric nervous system.
**Option B:** This option is incorrect because EMR is not typically used for the treatment of esophageal strictures, which are caused by chronic inflammation and scarring.
**Option C:** This option is incorrect because EMR is not a definitive treatment for invasive esophageal cancer, which requires more aggressive therapies such as surgery or chemotherapy.

**Clinical Pearl / High-Yield Fact**
It's essential for clinicians to recognize the limitations of EMR in treating Barrett's esophagus, particularly in cases of high-grade dysplasia or early cancer, where more definitive treatments may be necessary to prevent the progression to invasive cancer.

**Correct Answer:** D.