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
[{'content': 'Retinoblastoma spreads through? \nSelect and explain. \nA. Vascular invasion, B. Direct invasion, C. Optic nerve, D. Lymphatic', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]