Option 1: Young folded mountains are formed when two tectonic plates collide, causing the crust to fold and buckle. This process is caused by compression, not tension. Therefore, option 1 is incorrect.

Option 2: Similarly, old folded mountains are also formed by compression, not tension. Over time, the folded mountains erode and become more rounded. Hence, option 2 is also incorrect.

Option 3: Laccolith mountains are formed when magma pushes up between layers of sedimentary rock, creating a dome-shaped mountain. This process is not related to tension, but rather to the intrusion of magma. Therefore, option 3 is incorrect.

Option 4: Block mountains are formed when large blocks of the earth`s crust are uplifted or tilted along fault lines due to tensional forces. This creates steep, rugged mountain ranges with distinct fault lines. Option 4 is the correct answer.

Alert - correct answer should be option 2: Fold Mountains.