A. Class I lever
B. Class II lever
C. Class III lever
D. Wheel and axle
The correct answer is A. Class I lever
Most of the elevators used are class I or simple levers. The fulcrum (alveolar bone) is located between the applied force (hand of the operators) and the load or resistance (tooth).
Effort arm (distance between the fulcrum and the force applied) should be greater than resistance arm (distance between the fulcrum and the load or resistance i.e. Tooth).