**Core Concept:** Scleroderma is a connective tissue disease characterized by excessive collagen deposition in various organs, including the gastrointestinal tract. The oesophagus is one of the commonly affected organs, leading to oesophageal dysfunction.

**Why the Correct Answer is Right:** In scleroderma, the immune system mistakenly attacks the normal cells and tissues, causing inflammation and overproduction of collagen. In the oesophagus, this leads to fibrotic changes and narrowing of the lumen, resulting in dysphagia (difficulty in swallowing) and regurgitation.

**Why Each Wrong Option is Incorrect:**

A. Oesophageal involvement is not limited to a specific part of the oesophagus, as the disease affects the entire gastrointestinal tract.
B. While gastrointestinal manifestations do occur in systemic scleroderma, the correct answer is not limited to one part.
C. The correct answer is not limited to the upper oesophagus only; lower oesophageal involvement also occurs.
D. The correct answer is not limited to the gastrointestinal tract; systemic manifestations of scleroderma can affect multiple organs.

**Clinical Pearl:** The correct answer highlights the importance of considering oesophageal involvement in patients with systemic scleroderma, as early intervention can improve symptoms and prevent complications like strictures and Barrett's oesophagus.

**Correct Answer:** D. Scleroderma can affect the entire gastrointestinal tract, not just a specific part of the oesophagus. Involvement of the oesophagus in scleroderma may manifest as dysphagia, regurgitation, and chest pain, necessitating a thorough clinical examination and imaging studies to diagnose and monitor the disease progression.