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
Ramu, an 8-year old boy presented with pain in the arm. On x-ray, his upper end of humerus demonstrates an expansile lesion in the metaphysis with breach of the overlying cortex. Most likely diagnosis is - 
Select and explain. 
A. Aneurysmal bone cyst, B. Unicameral bone cyst, C. Chondroblastoma, D. Osteoclastoma
A: Aneurysmal bone cyst
Answer: A: Aneurysmal bone cyst 
Explanation: Here the diagnosis is aneurysmal bone cyst because the overlying cortex is breeched, which is not seen in unicameral bone cyst.