**Core Concept**
Primary Sjogren's syndrome is a chronic autoimmune disorder characterized by lymphocytic infiltration and destruction of exocrine glands, particularly the salivary and lacrimal glands. This leads to symptoms of dry mouth (xerostomia) and dry eyes (xerophthalmia).

**Why the Correct Answer is Right**
Primary Sjogren's syndrome is an autoimmune disorder where the immune system mistakenly attacks the exocrine glands. This results in inflammation and destruction of the glandular tissue, leading to the characteristic symptoms. The disease is associated with the presence of autoantibodies, such as anti-SSA/Ro and anti-SSB/La antibodies.

**Why Each Wrong Option is Incorrect**
**Option A:**
Primary Sjogren's syndrome is indeed an autoimmune disorder, so this statement is true.

**Option B:**
The disease is not caused by a viral infection, but rather by an autoimmune response. So, this statement is incorrect.

**Option C:**
The presence of anti-SSA/Ro and anti-SSB/La antibodies is a hallmark of Primary Sjogren's syndrome, so this statement is true.

**Option D:**
The disease can occur in isolation, without any other underlying autoimmune or connective tissue disease, making this statement true.

**Clinical Pearl / High-Yield Fact**
Primary Sjogren's syndrome can be associated with other autoimmune disorders, such as lupus, rheumatoid arthritis, and scleroderma. Patients with Primary Sjogren's syndrome are at an increased risk of developing these conditions.

**Correct Answer:** B. The disease is not caused by a viral infection.