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: Dental
Hard deposits found on tooth and appliances in an
uncleaned mouth is called 
Select and explain. 
A. Plaque, B. Calculus, C. Materia alba, D. None
B: Calculus
Answer: B: Calculus 
Explanation: None