7. Stress is the force applied to a rock, which may cause deformation of the rock. There are three major types of stress and go along with the three types of plate boundaries; Compression stress is common at convergent boundaries, tension stress at divergent boundaries, and the shear stress at transform boundaries. In this case the rocks have undergone tensional stresses.
8. Horst is a raised fault block bounded by normal faults. A horst is a raised block of the Earth's crust that has lifted, or has remained stationary, while the land on either side (garben) has subsided. Therefore the structure labeled A in the diagram is Horst.
9. A Graben; it is a valley with a distinct escarpment on each side caused by the displacement of a block downward. It often occurs side by side with the horsts. Horst and Graben structures indicate tensional forces and crustal stretching. Therefore, the structure labeled B is Graben.