Passage Summary: Seals can stay underwater for a very long time, and scientists believe they use their spleens as a sort of backup oxygen tank to help them do it.

Conclusion: Antarctic seals likely store oxygenated blood in their spleens to facilitate long underwater dives.

Reasoning: These seals stay submerged for long periods and utilize oxygen stored in their blood rather than just their lungs.

Analysis: Since this is a 'Strengthen EXCEPT' question, four choices will provide evidence for the spleen-oxygen hypothesis, while the correct answer will not. Supporting evidence would likely involve physical changes in the spleen during dives, such as the spleen contracting to pump blood into the system, or data showing the spleen contains high levels of red blood cells. Be careful with human behavior here—seals are quite different, so keep the focus on biological mechanisms. The odd one out might be a fact that is irrelevant to the spleen's function or one that describes a different organ entirely.