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
According to WHO 1986, a molar filled with temporary restoration is classified as: 
Select and explain. 
A. Sound tooth, B. Filled but decay, C. Filled with no decay, D. Decayed tooth
D: Decayed tooth
Answer: D: Decayed tooth 
Explanation: None