This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CNS Tumors, Subject name: Pathology
[{'content': 'A metastatic carcinoma in the brain of an adult, most often comes from a primary in the: \nSelect and explain. \nA. Stomach, B. Ovary, C. Oral cavity, D. Lung', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Metastatic carcinoma in the brain of an adult, most often comes from a primary in the Lung. The five most common primary sites are lung, breast, skin (melanoma), kidney, and gastrointestinal tract, accounting for about 80% of all metastases.', 'role': 'assistant'}]