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 of the following cannot been seen radiographically? 
Select and explain. 
A. Interproximal caries, B. Root caries, C. Deep caries, D. None of the above
D: None of the above
Answer: D: None of the above 
Explanation: None