Which of the following describes confining pressure?

Confining pressure refers to the pressure exerted on material when it is surrounded by other materials, typically in a geologic context. This pressure is applied uniformly in all directions, meaning that the force is not coming from just one source, like above, but is distributed evenly across the rock or sediment. This uniform application of pressure occurs in situations like deep underground where rocks are compressed by the weight of overlying material.

In contrast, pressure only from above does not capture the complete nature of confining pressure, as it disregards the additional horizontal pressures that are also at play. The idea of pressure caused by tectonic activity is more specific and does not accurately define confining pressure, which can exist without tectonic movements. Lastly, describing confining pressure as always low is misleading, as it can be quite high in deep geological settings, where the weight of overlying rock contributes significantly to the total confining pressure. Therefore, the definition that encapsulates the concept correctly is the one that describes how pressure is applied uniformly in all directions.