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: Unknown
A metastatic carcinoma in the brain of an adult most often comes from a primary in the - 
Select and explain. 
A. Stomach, B. Ovary, C. Oral cavity, D. Lung
D: Lung
Answer: D: Lung 
Explanation: answer: D