What is one example of a type of cave formation?

The correct answer is speleothems, as this term specifically refers to mineral formations found in caves that have been deposited by dripping water. Speleothems include various structures such as stalactites (which hang from the ceiling) and stalagmites (which rise from the ground). They are formed over long periods as minerals precipitate out of water dripping through the cave ceiling, creating intricate and beautiful natural sculptures.

While stalagmites can be considered a specific type of speleothem, the broader term “speleothems” encompasses all types of cave formations created by mineral deposits. This makes it the most accurate choice in the context of cave formations, providing a comprehensive understanding of the various structures that can be found within a cave environment. Other options like spelunk formations or sinkholes do not refer specifically to the mineral deposits formed in caves. Spelunking generally refers to the recreational exploration of caves, and sinkholes are geological depressions that can occur on the surface due to the erosion of the underlying soil or rock, not specific formations created within caves.