## **Core Concept**
The question tests the understanding of esophageal disorders, specifically those causing dysphagia. Dysphagia refers to difficulty swallowing, which can be progressive or non-progressive and may affect liquids, solids, or both. The symptoms and findings from the barium study point towards a mechanical obstruction.

## **Why the Correct Answer is Right**
The correct answer, **C. Peptic Stricture**, is the most likely diagnosis given the symptoms and barium study findings. Peptic stricture typically results from chronic gastroesophageal reflux disease (GERD), leading to inflammation and scarring of the distal esophagus. This condition causes non-progressive dysphagia initially for solids and later for liquids as well. The barium study findings of proximal esophageal dilatation with distal constriction are classic for a stricture. The distal constriction is where the stricture is located, causing the obstruction.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although it could cause dysphagia, the specific presentation and barium findings do not align as closely with the given scenario as peptic stricture does.
- **Option B:** This option might cause progressive dysphagia and does not specifically match the non-progressive nature for solids and the described barium findings.
- **Option D:** This option does not typically present with the described barium study findings and is less likely to cause the specific pattern of dysphagia mentioned.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that peptic strictures are a complication of long-standing GERD. Patients often have a history of heartburn and regurgitation. The presence of dysphagia for solids should prompt an investigation for GERD and possible complications like stricture.

## **Correct Answer: C. Peptic Stricture**