What type of simple machine is a catapult? ( incline plane , lever , pulley , screw , wedge, or a wheel and axle) how do you know ?

Lever

Explanation:

A catapult as a machine is a lever (1st class) because the fulcrum is between the Effort applied and the load(object) to be launched. A first class lever machine is a machine that has the fulcrum in between the effort and the load which makes a catapult a first class lever.

The handle of the catapult is where the effort is applied, the fulcrum is the point of contact between the rubber tied to the stick and the stick itself and the load is the object to be launched.