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: Radiology
Which lesion displays an ill-defined border? 
Select and explain. 
A. Periapical cyst, B. Sclerosing osteitis, C. Soft tissue capsule, D. Multiple myeloma
B: Sclerosing osteitis
Answer: B: Sclerosing osteitis 
Explanation: Ill-Defined Borders
Blending Border: A blending border is a gradual, often wide zone of transition between the adjacent normal bone trabeculae and the abnormal appearing trabeculae of the lesion. The focus of this observation is on the trabeculae and not on the radiolucent marrow spaces.
Examples of conditions with this type of margin are sclerosing osteitis and fibrous dysplasia.
Oral radiology White and Pharaoh; 7th ed. Page no 276,277