**Question:** All are true of achalasia cardia, except:

A. Achalasia cardia is a motor disorder of the esophagus.
B. The condition is characterized by impaired relaxation of the lower esophageal sphincter (LES).
C. Achalasia cardia is caused by a defect in the myenteric plexus.
D. The symptoms typically include regurgitation of undigested food and weight loss.

**Core Concept:** Achalasia cardia is a motor disorder of the esophagus, a rare disorder characterized by impaired relaxation of the lower esophageal sphincter (LES). It is caused by a defect in the myenteric plexus, which leads to dysfunction of the esophageal smooth muscles. This results in difficulty in swallowing and regurgitation of undigested food and weight loss.

**Why the Correct Answer is Right:**

Option A is incorrect because achalasia cardia is not a motor disorder of the stomach, but rather a motor disorder of the esophagus. The correct answer refers to the motor dysfunction affecting the esophagus and its smooth muscles, which is the primary pathological feature of achalasia cardia.

Option B is correct because the condition involves impaired relaxation of the lower esophageal sphincter (LES), which is essential for proper swallowing and prevents regurgitation of food and reflux of stomach contents into the esophagus.

Option C is incorrect because a defect in the myenteric plexus is not a defining feature of achalasia cardia. The myenteric plexus is a part of the autonomic nervous system involved in gut motility, but its dysfunction is not the primary cause of achalasia cardia. Instead, the primary cause is presumed to be a genetic or immune-mediated damage to the neurons in the myenteric plexus leading to loss of peristaltic function in the esophagus.

Option D is correct because the symptoms are typical of achalasia cardia and include difficulty in swallowing (dysphagia), regurgitation of undigested food, and weight loss. These symptoms arise due to the impaired peristaltic function of the esophagus, which results in inability to propel food effectively from the esophagus to the stomach.

**Why Each Wrong Option is Incorrect:**

Option A is incorrect because the primary feature of achalasia cardia is dysphagia (difficulty in swallowing) and regurgitation of undigested food. This option misdirects the student to focus on the stomach instead of the primary features of the disease.

Option B is incorrect because regurgitation of food is not a defining feature of achalasia cardia. The primary focus of achalasia cardia is on dysphagia (difficulty in swallowing) and regurgitation of undigested food, not weight loss. Weight loss is usually a late symptom in the disease progression and might be confused with other causes of weight loss.

Option C is incorrect because the primary focus of achalasia cardia is on dysphagia and regurgitation