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
Internal appearance of the lesion can be determined by the term: 
Select and explain. 
A. Discoid, B. Circular, C. Pedunculated, D. Mixed density
D: Mixed density
Answer: D: Mixed density 
Explanation: The internal appearance of a lesion can be classified into one of three basic categories:

Totally radiolucent
Totally radiopaque
Mixed radiolucent and radiopaque (mixed density).

A totally radiolucent interior is common in cysts, and a totally radiopaque interior is observed in osteomas. The mixed density internal structure is seen as the presence of calcified structures (white) against a radiolucent (black) backdrop.
Oral radiology White & Pharaoh 7th edition: page no 277