**Core Concept**
Achalasia cardia is a primary esophageal motility disorder characterized by the failure of the lower esophageal sphincter (LES) to relax, leading to difficulty in swallowing and regurgitation of food. The condition is often diagnosed using radiological tests that demonstrate characteristic findings.

**Why the Correct Answer is Right**
The correct answer is related to the radiological findings of achalasia cardia. The condition is often diagnosed using barium swallow studies, which show a characteristic "bird's beak" appearance of the esophagus due to the failure of the LES to relax. This results in a narrow, tapering esophageal lumen, with a dilated esophagus proximal to the LES.

**Why Each Wrong Option is Incorrect**
**Option A:** Not directly related to achalasia cardia, as it may be seen in other conditions such as esophageal stricture or cancer.
**Option B:** This is a characteristic finding of achalasia cardia, but option A is not. So we need to find the one which is not related.
**Option C:** This is a characteristic finding of achalasia cardia, but option A is not. So we need to find the one which is not related.
**Option D:** This is a characteristic finding of achalasia cardia, but option A is not. So we need to find the one which is not related.

**Clinical Pearl / High-Yield Fact**
Achalasia cardia is often associated with other conditions such as esophageal cancer, and patients with achalasia cardia should be screened regularly for these conditions. Additionally, the "bird's beak" appearance on barium swallow studies is a classic radiological finding of achalasia cardia.

**Correct Answer:** B.