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': 'Mesentric tumours are - \nSelect and explain. \nA. Usually solid, B. Usually cystic, C. Highly malignant, D. Highly vascular', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Mesentric tumors have been described as cystic in 40-60% of Cases.\nSolid primary tumors of mesentry are rare.', 'role': 'assistant'}]