**Core Concept**
Neuroblastoma is a type of pediatric cancer that originates from the sympathetic nervous system. The disease often presents with metastasis to regional lymph nodes, which is a result of the tumor's ability to spread through the lymphatic system.

**Why the Correct Answer is Right**
In neuroblastoma, the primary tumor often arises in the adrenal glands or along the sympathetic chain in the neck, chest, or abdomen. The cancer cells then gain access to the lymphatic system and begin to metastasize to nearby lymph nodes. This process is facilitated by the expression of neurotrophic factors and the presence of lymphatic vessels in the tumor microenvironment. The lymph nodes become involved early in the disease process, and their involvement is a critical prognostic factor.

**Why Each Wrong Option is Incorrect**
**Option A:** While the lungs are a common site of metastasis in many types of cancer, they are not the most common site in neuroblastoma. The lungs are involved in neuroblastoma, especially in advanced disease, but lymph nodes are more frequently affected.
**Option B:** The liver can be involved in neuroblastoma, especially in cases with widespread disease. However, it is not the most common site of metastasis. The liver is more commonly involved in other types of pediatric cancer, such as hepatoblastoma.
**Option D:** The vertebrae can be involved in neuroblastoma, especially in cases with bone metastasis. However, this is not the most common site of metastasis. Bone metastasis is less common than lymph node involvement in neuroblastoma.

**Clinical Pearl / High-Yield Fact**
In pediatric oncology, the presence of lymphadenopathy (lymph node enlargement) is a critical finding that warrants further investigation and staging. A thorough understanding of the lymphatic system and its role in cancer spread is essential for the management of neuroblastoma and other pediatric cancers.

**✓ Correct Answer: C. Lymph nodes**