Among small-to medium-sized marine mammals such as seals and dolphins, the longer an animal can stay submerged during a dive, the greater the depth the animal can reach.
Information
For seals and dolphins,
the longer can , the greater depth be submerged animal can reach
Dolphins can dive to greater depths than northern fur seals.
elephant seals can stay submerged longer than Weddell seals can.
Evaluate
On a Must Be False question, the correct answer almost always contradicts a conditional provided in the stimulus or an available inference we can make from the stimulus.
They didn't give us a conditional, but they gave us a Volume Dial relationship (aka Stepladder / Double-headed Line).
The way "the more x, the more y" seems to work is that we can always invert them and say "the less x, the less y", but we usually don't read them backwards (i.e. knowing something is more Y doesn't seem to definitively tell us more X).
However, in this context, the first sentence is saying if you listed all the seals and dolphins, the ones who rank higher on the "how long can stay submerged" scale also rank higher on the "how deep an animal can reach" scale.
So if you were to read the scale of , who ever is ranked #1 is also #1 on the .
We're told a head-to-head matchup between dolphins and northern fur seals seals, and one between elephant seals and W seals.
Goal
So we have two comparisons we can judge.
When it comes to "how long you can be submerged" / "how deep you can dive",
dolphins > northern fur seals elephant seal > Weddell seal
Those don't chain together, because we don't have any way to relate them to each other. So we'll just look for something to contradict one of these two.