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
A radio-opaque mass continuous with the cementoenamel junction attached to the distal surface of the first premolar is: 
Select and explain. 
A. Hyper Keratosis, B. Calculus, C. Food debris, D. Epithelial attachment
B: Calculus
Answer: B: Calculus 
Explanation: None