A distemper virus has caused two-thirds of the seal population in the North Sea to die since May 1988. The explanatio...

Mehran November 24, 2015

Thanks for your question, @GreenMachine. The key here is that the virus and the pollution are totally different things. This is a Strengthen logical reasoning question, and we are being asked to select the answer choice that most strengthens the argument in the stimulus. Let's first be sure we understand that argument correctly.

The conclusion of the stimulus is that it was the severe pollution of the North Sea that weakened the seals' immune system so that they were more vulnerable to the virus. This is cause and effect reasoning, and the root cause is argued to be the pollution, NOT the virus. We need to find the answer choice that supports this case and effect theory.

Answer choice (A) does so. It talks about other species that are in the North Sea and thus subject to the severe pollution identified in the stimulus as the cause for the seals' vulnerability. It also indicates that other species have suffered declines in population — not necessarily from the distemper virus, but perhaps because of the exposure to the pollution noted.

Hope this helps. Please let us know if you have any other questions!