Final answer:
A thrust fault is a low-angle, reverse fault resulting from compressional stress leading to the hanging wall moving upwards over the footwall.
Step-by-step explanation:
A thrust fault is best described as b. a low-angle, reverse fault. These faults are formed by compressional stresses which cause the hanging wall to move upwards over the footwall. A thrust fault's dip is generally less than 30° and often occurs during the compression and shortening of the Earth's crust, characteristic of mountain-building processes. Thrust faults are distinguished from normal faults, in which the hanging wall moves down relative to the footwall, and strike-slip faults, which involve horizontal movement. The Copper Creek Thrust Fault in the Appalachian Mountains is an example where an allochthonous block, or the piece of the Earth's crust that has been moved, is thrust on top of the autochthonous block, or the original position of the Earth's crust. This is a common feature in areas of tectonic collision, where large segments of the Earth's crust are pushed over one another, leading to the formation of mountain ranges.