**Core Concept**
Kawasaki's disease is a medium-vessel vasculitis that primarily affects children, causing inflammation of the blood vessels and potentially leading to coronary artery aneurysms. The treatment aims to reduce inflammation and prevent long-term cardiovascular complications.

**Why the Correct Answer is Right**
The treatment of Kawasaki's disease involves a multi-faceted approach, including the administration of intravenous immunoglobulin (IVIG) to reduce inflammation and the use of aspirin to prevent thrombosis. IVIG works by modulating the immune response, reducing the production of pro-inflammatory cytokines, and promoting the production of anti-inflammatory cytokines. This helps to reduce the severity of the disease and prevent long-term complications such as coronary artery aneurysms.

**Why Each Wrong Option is Incorrect**
**Option A:** Corticosteroids are not the primary treatment for Kawasaki's disease, as they may actually increase the risk of coronary artery aneurysms.
**Option B:** Antiviral medications are not effective in treating Kawasaki's disease, as the disease is caused by an autoimmune response rather than a viral infection.
**Option C:** Plasma exchange is not a standard treatment for Kawasaki's disease, as IVIG is the preferred treatment.

**Clinical Pearl / High-Yield Fact**
The administration of IVIG within the first 10 days of symptom onset is associated with a reduced risk of coronary artery aneurysms and other long-term complications.

**Correct Answer:** C.