Passage Summary: Among medium-sized sea mammals, the longer you can hold your breath, the deeper you can go. We know dolphins go deeper than fur seals, and elephant seals can stay under longer than Weddell seals.

Reasoning: For certain marine mammals, dive depth is directly proportional to submersion time. Dolphins dive deeper than fur seals, and elephant seals stay submerged longer than Weddell seals.

Analysis: In a Must be False scenario, we are looking for a statement that directly contradicts the established rules. The stimulus establishes a strict correlation: longer time equals greater depth. Since elephant seals stay submerged longer than Weddell seals, the rule dictates they must also be able to reach greater depths. Therefore, any statement claiming that Weddell seals can reach greater depths than elephant seals would be a logical impossibility based on the provided facts.