**Core Concept**
Henoch-Schönlein purpura (HSP) is a form of vasculitis characterized by the deposition of IgA immune complexes in small blood vessels, leading to inflammation and damage.

**Why the Correct Answer is Right**
The deposition of IgA immune complexes in small blood vessels is a hallmark of HSP, causing inflammation and damage to the affected tissues. This leads to the characteristic symptoms of non-blanching purpura, abdominal pain, and arthritis. The colicky abdominal pain in this case is likely due to inflammation of the gastrointestinal tract, a common feature of HSP. The presence of IgA immune complexes is a key diagnostic clue, distinguishing HSP from other forms of vasculitis.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely incorrect because Henoch-Schönlein purpura is not typically associated with the deposition of IgG or IgM immune complexes.
* **Option B:** This option may be a distractor, but it is not the most likely diagnosis given the presence of IgA immune complexes and the characteristic symptoms of HSP.
* **Option D:** This option is incorrect because Kawasaki disease is a different form of vasculitis that is more commonly seen in children, but it is not associated with the deposition of IgA immune complexes.

**Clinical Pearl / High-Yield Fact**
HSP is a classic example of a vasculitis that affects small blood vessels and is associated with the deposition of IgA immune complexes. It is essential to consider this diagnosis in children presenting with non-blanching purpura, abdominal pain, and arthritis.

**Correct Answer:** C.