In the late 1980s, the population of sea otters in theNorth Pacific began to decline. Thereare two plausible explanations for the decline: predation, possibly by killer whales, or disease. Of these two, disease is the more likely,since a concurrent sharp decline in populations of seals and sea lions isbelieved to have been caused by disease, and diseases that infect thesecreatures are likely to be able to infect sea otters also.

　　Which of the following, if true, most seriously weakensthe reasoning?

　　(A)Killer whales in the North Pacific usually prey on seals and sea lions butwill, when this food source is scarce, seek out other prey.

　　(B) There is no indication that the sea otter populationat any North Pacific location declined in the 1980s because of substantialnumbers of sea otters migrating to other locations.

　　(C) Along the Pacific coast of North America in the1980s, sea otters were absent from many locations where they had beenrelatively common in former times.

　　(D) Following the decline in the population of the seaotters, there was an increase in the population of sea urchins, which are seaotters' main food source.

　　(E) The North Pacific populations of seals and sea lionscover a wider geographic area than does the population of sea otters.

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