Which of the following factors determines the strength of the frictional force between two surfaces?

The amount of heat generated by the frictional

The types of surfaces involved

The objects' sizes

How hard the surfaces push together

Types of surface and how hard they push together

option 2 and 4

Explanation:

The strength of frictional force depends on the types of forces involved and how hard the surfaces push together.

If the surfaces are rough, then the frictional force between two surfaces is more and if the surfaces are smooth, the frictional force between two surfaces is less.

If they push hard, it means the weight on the surface is more and thus, the normal reaction force is more.

Friction force is directly proportional to the normal reaction force, so, the friction force depends on the push.