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: Orthopaedics
True about osteoclastoma 
Select and explain. 
A. Mononuclear cells are malignant component, B. Common in elderly, C. Radiotherapy is the main modality of treatment, D. Diaphyseal lesion
A: Mononuclear cells are malignant component
Answer: A: Mononuclear cells are malignant component 
Explanation: None