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 lever action that occurs in distal extension partial dentures is 
Select and explain. 
A. 1st - order Lever, B. 2nd - order lever, C. 3rd - order lever, D. 4th - order lever
A: 1st - order Lever
Answer: A: 1st - order Lever 
Explanation: None