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': 'Which of the following carcinoma most frequently metastasizes to brain? \nSelect and explain. \nA. Small cell carcinoma lung, B. Prostate cancer, C. Rectal carcinoma, D. Endometrial cancer', 'role': 'user'}, {'content': 'Answer: A \nExplanation: . Small cell carcinoma lung', 'role': 'assistant'}]