The correct response is:
1; 2; 3
Here's the reasoning:
- A class 1 lever can have mechanical advantage, depending on the distances from the fulcrum to the effort and load.
- A class 2 lever always has a mechanical advantage because the load is between the fulcrum and the effort.
- A class 3 lever typically does not have a mechanical advantage as the effort is applied between the fulcrum and the load, but it can also have mechanical advantage depending on the user and application.