Which geological process primarily shapes the formations within caves?

The correct choice is focused on the geological process known as corrosion, which plays a significant role in shaping cave formations. Corrosion refers to the chemical dissolution of minerals in rock, particularly limestone, which is a common material in many caves. This process is typically facilitated by slightly acidic water, often formed when carbon dioxide from the atmosphere or soil combines with water to create carbonic acid. As this acidic water seeps through limestone, it reacts with the calcium carbonate, leading to the formation of various structures such as stalactites, stalagmites, and other speleothems.

In contrast, while weathering contributes to the breakdown of rock material, it is more associated with the physical disintegration of rocks rather than the specific chemical processes that create cave formations. Metamorphism involves changes in the structure and composition of rocks under heat and pressure, which does not directly pertain to the formation of caves. Subduction refers to tectonic plates colliding and one sliding beneath another; while it can influence the broader geological landscape, it is not a primary driver of the specific features found within cave systems. Thus, corrosion is the most relevant process for understanding how caves and their formations develop over time.