The correct answer is - c. fault.
The faults are a geological feature that appears on places where the boundaries of the tectonic plates are, or in close proximity tot he same. Basically, the faults are cracks in the Earth's crust, usually parallel to the boundaries of the plates. The faults can be experiencing vertical or horizontal pressures, and that will determine their size, length, shape. This geological feature is also a nice indicator as to where the chances are very high that an earthquake will appear, as it is located above the places where the crust is experiencing adjustments deep inside.
