**Core Concept**
Hypersensitivity angitis refers to a type of blood vessel inflammation characterized by the deposition of immune complexes, leading to vasculitis. This condition is often associated with autoimmune disorders or infections.

**Why the Correct Answer is Right**
Henoch-Schönlein purpura (HSP) is a classic example of hypersensitivity angitis, also known as vasculitis. It is an IgA-mediated autoimmune disorder that primarily affects small blood vessels, particularly the capillaries, venules, and arterioles. The immune complex deposition in these vessels triggers an inflammatory response, leading to the characteristic skin purpura, joint pain, abdominal pain, and glomerulonephritis. HSP typically affects children and young adults, but it can occur at any age.

**Why Each Wrong Option is Incorrect**
**Option A:** Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disorder that can cause vasculitis, but it is not typically characterized as hypersensitivity angitis. SLE has a more complex pathophysiology involving multiple autoantibodies and immune complexes.

**Option B:** Polyarteritis nodosa (PAN) is a medium- and small-vessel vasculitis that primarily affects the arteries, rather than the capillaries and venules. PAN is not typically associated with hypersensitivity angitis.

**Option D:** Buerger's disease, also known as thromboangiitis obliterans, is a non-atherosclerotic, segmental inflammatory disease of the small and medium-sized arteries and veins. While it does involve inflammation, it is not typically classified as hypersensitivity angitis.

**Clinical Pearl / High-Yield Fact**
Hypersensitivity angitis, including Henoch-Schönlein purpura, is often characterized by the deposition of IgA immune complexes in small blood vessels. Remember the acronym "IgA - Immune Complex - Angitis" to associate this condition with IgA-mediated immune responses.

**✓ Correct Answer: C. Henoch schonlein purpura**