In the late 1980s,the population of sea otters in the North Pacific began to decline.There are 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 is believed to have been caused by disease,and diseases that infect these creatures are likely to be able to infect sea otters also.
Which of the following,if true,most seriously weakens the reasoning?
【选项】Killer whales in the North Pacific usually prey on seals and sea lions but will,when this food source is scarce,seek out other prey.
选项是否正确？