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 appliance used to treat thumbsucking: 
Select and explain. 
A. Crib appliance, B. Frankel appliance, C. Bionator, D. Activator
A: Crib appliance
Answer: A: Crib appliance 
Explanation: None