The most satisfactory explanation for the formation of fold mountain is

Step 1: Analyze the question The question asks for the best explanation of how fold mountains form. Fold mountains are large mountain ranges made of bent, wrinkled layers of rock, such as the Himalayas, Alps, Rockies, and Andes.

Step 2: Explain the concept Fold mountains form from sedimentary rocks that were laid down in large depressions called geosynclines. Plate movement then pushes the edges of the depression toward each other. This pushing is called compression, and it works as follows:

1. Sediments build up in a geosyncline, a long, shallow sea.
2. Two crustal plates (or sections of crust) move toward each other.
3. The compressional forces squeeze the sediments sideways.
4. The layers buckle into upfolds (anticlines) and downfolds (synclines).
5. Over millions of years, the folded rocks are uplifted into mountain ranges.

Step 3: Evaluate each option

• A. Faulting: This is the fracturing and displacement of rock. It produces block (horst) mountains and rift valleys, not fold mountains.
• B. Vulcanicity: This is the movement of molten rock (magma) toward or onto the surface. It forms volcanic mountains, not fold mountains.
• C. Compressional forces: These squeeze rock layers horizontally, causing them to fold. This is the direct cause of fold mountains.
• D. Tensional forces: These pull the crust apart. They cause faulting and rift valleys, not folding.

Step 4: Answer The most satisfactory explanation is compressional forces.

Exam tip: Remember the pairing:

• Compression → Folding (fold mountains)
• Tension → Faulting (rift valleys, block mountains)
• Magma → Vulcanicity (volcanoes)

If you see "fold" in the question, think "compress, like squeezing a rug or tablecloth from both sides."