Which of the following is a characteristic feature of caves found in limestone?

Stalactites and stalagmites are indeed characteristic features of caves formed in limestone. These formations occur due to the processes of mineral deposition from dripping water. When water that is rich in calcium carbonate seeps through the limestone, it deposits minerals as it evaporates. Stalactites form from the ceiling of the cave where the dripping begins, while stalagmites develop on the cave floor directly under the stalactites as the dripping water continues to deposit minerals over time.

These features are specific to limestone caves because limestone is soluble in weak acids, especially carbonic acid found in natural water. This solubility not only helps in creating the cave's structure but also facilitates the formation of the beautiful stalactites and stalagmites that characterize these environments, making them a defining element of limestone karst formation.

In contrast, wide openings, flat floors, and high temperatures are not defining features of limestone caves. While some caves may have wide openings or flat floors, these characteristics can vary widely and are not exclusive or essential to limestone caves in the same way that stalactites and stalagmites are. High temperatures are also not a typical feature of limestone caves, which often maintain cooler conditions due to the underground environment.