逻辑问题麻烦帮忙

skyeH

麻烦有空的朋友帮忙看看这道题目，选个答案

Between1980 and 2000 the sea otter population of the Aleutian Islands declinedprecipitously. There were no signs of disease or malnutrition, so there wasprobably an increase in the number of otters being eaten by predators. Orcaswill eat otters when seals, their normal prey, are unavailable, and theAleutian Islands seal population declined dramatically in the 1980s. Therefore,orcas were most likely the immediate cause of the otter population decline.

Which of the following, if true, moststrengthens the argument?

• The population of sea urchins, the main foodof sea otters, has increased since the sea otter population declined.
• Seals do not eat sea otters, nor do theycompete with sea otters for food.
• Most of the surviving sea otters live in a baythat is inaccessible to orcas.
• The population of orcas in the AleutianIslands has declined since the 1980s.
• An increase in commercial fishing near theAleutian Islands in the 1980s caused a slight decline in the population of thefish that seals use for food.
  
  

谢谢

闭眼看书

选3吧
大多数存活的otter生活在一个orcas接触不到的地方，也就是生活在可以被orcas接触到的海湾中的otter存活率低 无因无果

skyeH

闭眼看书 发表于 2017-1-30 12:56
选3吧
大多数存活的otter生活在一个orcas接触不到的地方，也就是生活在可以被orcas接触到的海湾中的otter ...

thank you