**Core Concept**
Lichen planus is a chronic inflammatory mucocutaneous condition characterized by a T-cell mediated immune response. The histological findings in lichen planus are crucial for diagnosis and include distinctive changes in the skin and mucous membranes.

**Why the Correct Answer is Right**
The characteristic histological feature of lichen planus is the presence of **basal cell degeneration**, accompanied by a band-like **inflammatory infiltrate** consisting of T-lymphocytes and histiocytes. This infiltrate is typically seen in the **papillary dermis**, just beneath the **epidermis**. The basal cells in the epidermis are often **degenerated** or **destroyed**, leading to a characteristic loss of cohesion between the epidermis and the dermis. Additionally, **colloid bodies** (also known as Civatte bodies or apoptotic bodies) are frequently seen in the dermis, indicating programmed cell death of the basal cells.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the histological findings in lichen planus. While some conditions may exhibit a similar inflammatory infiltrate, the presence of basal cell degeneration and colloid bodies is specific to lichen planus.
**Option B:** This option is incorrect because it is a characteristic feature of psoriasis, not lichen planus. In psoriasis, the primary histological finding is the presence of **parakeratosis**, which is the retention of nuclei in the stratum corneum.
**Option C:** This option is incorrect because it describes the histological findings in pemphigus vulgaris, a different autoimmune skin condition. In pemphigus vulgaris, the characteristic finding is the presence of **acantholysis**, which is the separation of keratinocytes from each other due to the loss of intercellular connections.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the histological findings in lichen planus can be variable and may not always be diagnostic. However, the presence of basal cell degeneration and colloid bodies in conjunction with a band-like inflammatory infiltrate is highly suggestive of lichen planus.

**Correct Answer: C. Acantholysis**