Final answer:
The correct answer is a strike-slip fault, which occurs when the displacement is parallel to the strike of the fault and involves horizontal movement of the fault walls.
Step-by-step explanation:
If displacement is parallel to the strike of the fault, then the fault is a strike-slip fault.
The blocks on either side of a fault are referred to as walls. When these walls move horizontally in opposite directions alongside the fault, this movement is characteristic of a strike-slip fault. If the orientation of the fault was vertical, it would indeed be identified as a strike-slip fault. In contrast, a fault with a non-vertical dip where one wall lies over the other, with a vertical displacement between the walls, would be classified as a dip-slip fault. This latter category includes normal faults, which result from extensional forces causing the hanging wall to move down, and reverse faults, which occur when compressional forces drive the hanging wall upwards.
Dip-slip motion can also occur in thrust faults, a type of reverse fault with a gentle dip that is less than 30°. Thrust faults involve the allochthonous block moving over the autochthonous block. Oblique-slip faults are those with both strike-slip and dip-slip movement.