**Core Concept**
Sjogren's syndrome is a chronic autoimmune disease characterized by lymphocytic infiltration and destruction of the exocrine glands, particularly the salivary and lacrimal glands. The parotid gland biopsy is a diagnostic tool used to assess the extent of lymphocytic infiltration and glandular destruction.

**Why the Correct Answer is Right**
In Sjogren's syndrome, the parotid gland biopsy typically shows a mononuclear cell infiltrate, predominantly composed of T lymphocytes and plasma cells. The lymphocytes infiltrate the glandular tissue, leading to destruction of the acinar and ductal cells, resulting in decreased salivary gland function. The presence of these lymphocytes and the characteristic destruction of the glandular tissue are diagnostic hallmarks of Sjogren's syndrome.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not specified, but in general, a biopsy showing normal glandular tissue would not be consistent with Sjogren's syndrome.
**Option B:** A biopsy showing only fibrosis or chronic inflammation might be seen in other conditions, such as chronic sialadenitis, but it is not diagnostic for Sjogren's syndrome.
**Option C:** A biopsy showing granulomatous inflammation is more characteristic of sarcoidosis or other granulomatous conditions, rather than Sjogren's syndrome.

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

**Correct Answer:** D.