**Core Concept**
Neuroblastoma is a pediatric cancer that arises from the neural crest cells of the adrenal medulla. The prognosis of neuroblastoma is influenced by various genetic and histopathological factors. Understanding these factors is crucial for determining the treatment plan and predicting patient outcomes.

**Why the Correct Answer is Right**
Evidence of gangliocytic differentiation is actually a favorable prognostic factor in neuroblastoma. Gangliocytic differentiation refers to the presence of mature ganglion cells in the tumor, which is a sign of tumor maturation. This histological feature is often associated with a better prognosis and a higher likelihood of spontaneous regression. In contrast, the other options are all considered poor prognostic factors.

**Why Each Wrong Option is Incorrect**
**Option A:** MYCN amplification is a common genetic abnormality in neuroblastoma, which is associated with advanced disease, metastasis, and a poor prognosis.
**Option B:** A high mitosis-karyorrhexis index is a measure of the tumor's aggressiveness, indicating a high rate of cell division and death. This feature is often seen in more aggressive neuroblastomas with a poor prognosis.
**Option D:** Mutations of neuritogenesis genes, such as TRK genes, can lead to the activation of oncogenic pathways and contribute to the development of neuroblastoma. These mutations are often associated with a poor prognosis.

**Clinical Pearl / High-Yield Fact**
When evaluating neuroblastoma, it's essential to assess the tumor's histopathological features, including the presence of gangliocytic differentiation. A high mitosis-karyorrhexis index and MYCN amplification are red flags indicating a more aggressive disease, while mutations of neuritogenesis genes can contribute to tumor development and progression.

**✓ Correct Answer: C. Evidence of gangliocytic differentiation.**