The correct answer is B.
Fault block mountains form when faults or cracks in the earth's crust force materials or blocks of rocks downward and others upwards.
This happens when instead of the earth folding over, the earth's crust pulls apart breaking up into chunks or blocks . These blocks get stacked on each other with some projecting up above the surface of the crust forming a mountain. Such mountains usually have a steep front side and a sloping back side.
