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: Gynaecology & Obstetrics
[{'content': 'Endometriomas on ultasound appear as \nSelect and explain. \nA. Solid with diffuse internal low-level echoes., B. Solid with focal internal low-level echoes., C. Cystic with diffuse internal low-level echoes., D. Cystic with focal hyperechoic internal echoes.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Endometrioma \xa0classically is cystic with homogenous, low-level internal echoes, i.e ground-glass echogenicity.', 'role': 'assistant'}]