Passage Summary: Divers found an underwater cave in the Mediterranean that is full of stalagmites, which are rock pillars usually created by dripping water.

Reasoning: Stalagmites are formed by water dripping onto a cave floor over time, yet this specific cave is currently filled with seawater and accessible only via an underwater tunnel.

Analysis: Since this is a 'Most Strongly Supported' question, we need to find a logical inference based on the provided facts. The key is the presence of stalagmites; these structures require air and dripping water to form, which cannot happen if the cave is submerged in seawater. Therefore, we can reasonably infer that the cave was not always underwater. Look for an answer choice that suggests the sea level was lower or the cave was dry at some point in the geological past.