**Core Concept**
Psoriasis is a chronic autoimmune skin condition characterized by hyperproliferation of keratinocytes, leading to thickening of the epidermis and formation of scaly plaques. The pathophysiology involves an interplay between genetic predisposition, immune system dysregulation, and environmental triggers.

**Why the Correct Answer is Right**
The most common type of psoriasis is plaque psoriasis, accounting for approximately 80-90% of all psoriasis cases. This type is characterized by well-demarcated, erythematous plaques with silvery scales, typically found on the elbows, knees, scalp, and lower back. The immune system plays a key role in the development of plaque psoriasis, with T cells, particularly CD4+ T cells, playing a central role in the inflammatory process. The activation of T cells leads to the release of various cytokines, including tumor necrosis factor-alpha (TNF-alpha), which promotes the proliferation of keratinocytes and the formation of plaques.

**Why Each Wrong Option is Incorrect**
**Option A:** Psoriatic arthritis is a type of psoriasis that primarily affects the joints, rather than the skin.
**Option B:** Inverse psoriasis is a rare type of psoriasis characterized by smooth, red patches in the folds of the skin, typically found in the groin, armpits, and under the breasts.
**Option C:** Guttate psoriasis is a type of psoriasis characterized by small, pink spots on the skin, often appearing after a bacterial infection, such as strep throat.

**Clinical Pearl / High-Yield Fact**
Psoriasis is a systemic disease that can increase the risk of cardiovascular disease, diabetes, and depression, making it essential to manage the condition not only through topical treatments but also through lifestyle modifications and systemic therapies.

**Correct Answer:** C. Guttate psoriasis