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
An example of preadjusted appliance is 
Select and explain. 
A. Frankel appliance, B. Begg's light wire appliance, C. Angles edge wire appliance, D. Andrew's straight wire appliance
D: Andrew's straight wire appliance
Answer: D: Andrew's straight wire appliance 
Explanation: None