Caves can be classified into various categories. Which of the following is NOT one of those categories?

Caves are typically classified into several categories based on their formation processes and characteristics. Among the common categories are solution caves, glacier caves, and lava caves.

Solution caves are formed primarily through the dissolution of soluble rocks, such as limestone, by slightly acidic water. This is a widespread category and is what most people think of when referring to caves. Glacier caves are created by the melting of ice in glacial environments, where the movement of ice creates natural passages. Lava caves form as a result of volcanic activity when lava flows and creates hollow tubes as it cools and solidifies.

The classification of caves does not typically include a category labeled "rock caves." While many caves are found within rock formations, this term is too broad and nonspecific. It does not describe a particular formation process or feature that distinguishes it from other cave types. Therefore, the answer identifying "rock caves" as not being recognized as a formal category within cave classification is accurate and highlights the specialized nature of cave types based on their formation processes.