This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Zellballen pattern on histopathology is observed in 
Select and explain. 
A. GIST, B. Astrocytoma, C. Carotid body tumor, D. Retinoblastoma
C: Carotid body tumor
Answer: C: Carotid body tumor 
Explanation: None