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
CALCULUS all are true except: 
Select and explain. 
A. Supragingival calculus is brown in colour, B. Hard and gritty, C. Calcified from plaque, D. Subgingival calculus is more difficult to remove than supragingival calculus
A: Supragingival calculus is brown in colour
Answer: A: Supragingival calculus is brown in colour 
Explanation: None