**Core Concept**
Henoch Schonlein purpura (HSP) is a form of vasculitis that primarily affects small blood vessels. It is characterized by the deposition of IgA immune complexes, leading to inflammation and damage to the affected vessels. HSP typically presents with a tetrad of symptoms: purpura, arthritis, abdominal pain, and renal involvement.

**Why the Correct Answer is Right**
The correct answer is a feature of HSP because it is a manifestation of the underlying immune complex deposition and vascular inflammation. In HSP, the deposition of IgA immune complexes triggers the activation of the complement system and the release of various cytokines, leading to the characteristic symptoms. The correct answer is a direct consequence of the pathophysiological process involved in HSP.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is a classic feature of HSP. The characteristic purpura is a result of the immune complex deposition and vascular inflammation. It is a hallmark symptom of the disease.
**Option B:** This option is incorrect because it is also a common feature of HSP. The arthritis is thought to be due to the deposition of immune complexes in the joints, leading to inflammation and pain.
**Option C:** This option is incorrect because it is a rare feature of HSP. While some patients may experience neurological symptoms, it is not a common or characteristic feature of the disease.

**Clinical Pearl / High-Yield Fact**
One key feature of HSP is its predilection for affecting small blood vessels, particularly in the skin, joints, and kidneys. This is in contrast to other forms of vasculitis that may affect larger vessels.

**Correct Answer: C.**