Which force created. a fault-block mountain?

Tensional force created a fault block mountain.

Explanation:

Mountains are composed of arrangement of rocks in a defined layer. Sometimes, they are created by tension in the tectonic plates and sometimes by frictional force between two plates will enlarge the rocks. Like this one kind of mountain formation is fault block mountain. So these mountains are made up of fault blocks.

Fault blocks are nothing but the broken crusts or tectonic plates due to tensional force in the Earth crust. So those broken crust can increase in the fault between two large rocks leading them to pull apart leaving a part in the middle.

And the middle portion will be hanging like a mountain. So this tensional force pulling the rocks present above the respective tectonic plates leads to the formation of fault block mountains.