**Core Concept**
Wilson disease is an autosomal recessive genetic disorder characterized by excessive accumulation of copper in the body, particularly in the liver, brain, and other organs. This accumulation leads to oxidative stress, mitochondrial dysfunction, and ultimately, cell death.

**Why the Correct Answer is Right**
The major clinical manifestation of Wilson disease in children 8-16 years of age is acute liver failure. This is due to the toxic effects of copper on the liver cells, leading to necrosis and inflammation. The liver enzyme levels, such as alanine transaminase (ALT) and aspartate transaminase (AST), are typically elevated in these patients.

**Why Each Wrong Option is Incorrect**
**Option A:** Kayser-Fleischer rings are a hallmark of Wilson disease, but they are not the major clinical manifestation in children 8-16 years of age.
**Option B:** Neurological symptoms, such as tremors and ataxia, can occur in Wilson disease, but they are not the primary manifestation in this age group.
**Option C:** Hepatomegaly (enlarged liver) can be a sign of liver disease, but it is not specific to Wilson disease and can be caused by other conditions.

**Clinical Pearl / High-Yield Fact**
Kayser-Fleischer rings, which are deposits of copper in the cornea, are a classic sign of Wilson disease and can be detected by a slit-lamp examination.

**Correct Answer: C. Hepatic failure.**