Question

Guillemots are birds of Arctic regions. They feed on fish that gather beneath thin sheets of floating ice, and they nest on nearby land. Guillemots need 80 consecutive snow-free days in a year to raise their chicks, so until average temperatures in the Arctic began to rise recently, the guillemots' range was limited to the southernmost Arctic coast. Therefore, if the warming continues, the guillemots’ range will probably be enlarged by being extended northward along the coast.
Which of the following, if true, most seriously weakens the argument?

• A. Even if the warming trend continues, there will still be years in which guillemot chicks are killed by an unusually early snow.
• B. If the Arctic warming continues, guillemots’ current predators are likely to succeed in extending their own range farther north.
• C. Guillemots nest in coastal areas, where temperatures are generally higher than in inland areas.
• D. If the Arctic warming continues, much of the thin ice in the southern Arctic will disappear.
• E. The fish that guillemots eat are currently preyed on by a wider variety of predators in the southernmost Arctic regions than they are farther north.

Hint:

When evaluating environmental arguments, consider the interactions between different species and how changes affect both competitors and prey.

Answer 1

The Correct Option is B

Step 1: Understanding the argument.
The argument is based on the assumption that if the Arctic warms, guillemots will extend their range northward. However, if their predators can also extend their range, this could counterbalance the expansion of the guillemots’ range.
Step 2: Analyzing the options.
- (A) This does not weaken the argument significantly, as it only suggests that snow may still impact the guillemots, but it doesn’t address the expansion of their range.
- (B) This is the correct answer. If guillemots’ predators can extend their range as well, it would reduce the effectiveness of the guillemots’ range expansion, making this a serious counterpoint to the argument.
- (C) This fact is not directly relevant to whether the guillemots’ range will expand.
- (D) The disappearance of thin ice does not directly undermine the argument about range expansion; it might only limit the guillemots' habitat in certain areas.
- (E) This introduces a potential issue for the guillemots but doesn’t directly address the northward range expansion.
Step 3: Conclusion.
The correct answer is (B), as it introduces a competing factor that could prevent the guillemots’ range from expanding northward.