It can be inferred from the passage that by describing the Weddell seal as preparing "for the worst”, biologists mean that it:
Exhibits physiological behavior similar to that which characterizes its longest dives in the wild
The author has stated in the last two lines of the passage that the Weddell Seal behaves different in the laboratory from what it does in the wild. Regardless of the length and depth of the dive it also behaves in a way it generally behaves when it goes for its long dives in the wild. Hence, it is evident that answer option (c) is the right answer choice.