In the context of geology, what is a fault-block mountain?

A fault-block mountain is indeed a type of mountain that is primarily formed through tectonic activities. This process involves the movement of the Earth's crust due to tectonic forces, leading to the fracturing and displacement of rock layers. As blocks of crust are uplifted along these tectonic faults, they create steep, rugged terrain characteristic of fault-block ranges. These mountains typically have a linear or elongated shape and are often found at divergent margins or zones of crustal stretching.

In contrast, the other options describe different geological formations. Volcanic mountains arise from the eruption of magma, while mountains formed by glacial activity are shaped through the erosive force of glaciers. Lastly, a mountain that is flat on top is referred to as a plateau, which is distinct from the steep and rugged profiles of fault-block mountains. This knowledge helps in understanding the various geological processes that shape our planet's landscape.