**Core Concept**
Systemic sclerosis is a chronic autoimmune disease characterized by fibrosis and vascular alterations in the skin and internal organs. The disease can be classified into two main forms: limited systemic sclerosis (also known as limited cutaneous systemic sclerosis) and diffuse systemic sclerosis. The limited form primarily affects the skin distal to the elbows and knees, whereas the diffuse form affects the skin more extensively, often involving the upper limbs and face.

**Why the Correct Answer is Right**
The diffuse form of systemic sclerosis is more likely to be associated with systemic manifestations such as renal involvement, pulmonary hypertension, and cardiac disease. This is because the diffuse form tends to involve the internal organs more extensively, leading to a greater risk of systemic complications. The pathophysiology of systemic sclerosis involves the activation of fibroblasts, which produce excessive amounts of collagen, leading to fibrosis. In the diffuse form, this process is more widespread, resulting in a higher risk of systemic involvement.

**Why Each Wrong Option is Incorrect**
**Option A:** Pulmonary fibrosis is a common manifestation of both limited and diffuse systemic sclerosis, and is not more specific to the diffuse form.
**Option B:** Raynaud's phenomenon is a common symptom of systemic sclerosis, but is not more likely to be found in the diffuse form than in the limited variant.
**Option C:** Esophageal dysmotility is a common manifestation of systemic sclerosis, and is not more specific to the diffuse form.

**Clinical Pearl / High-Yield Fact**
A key clinical feature that distinguishes the diffuse form of systemic sclerosis from the limited variant is the presence of systemic manifestations, such as renal involvement or pulmonary hypertension. This is an important consideration in the management and prognosis of patients with systemic sclerosis.

**Correct Answer: C. Pulmonary involvement.**