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
The direct retainer of choice when the principle abutment tooth has Lost its periodontal support is: 
Select and explain. 
A. Embrasure clasp, B. Ring clasp, C. Multiple circlet clasp, D. Onlay clasp
C: Multiple circlet clasp
Answer: C: Multiple circlet clasp 
Explanation: None