3. Which process acts on rock to form fault-block mountains? A. shear B. tension C. compression

To determine which process acts on rock to form fault-block mountains, let's analyze the options: 1. **Shear**: This process involves forces that cause layers of rock to slide past each other. While shear can create various geological features, it is not primarily responsible for the formation of fault-block mountains. 2. **Tension**: This process involves pulling forces that stretch the Earth's crust. Tension can lead to the formation of rift valleys and can contribute to the development of fault-block mountains, but it is not the primary process. 3. **Compression**: This process involves forces that push rocks together. Compression can lead to the folding and faulting of rocks, which is a key mechanism in the formation of fault-block mountains. Based on this analysis, the correct answer is: **C. compression** Compression is the primary process that acts on rock to form fault-block mountains.