captainfriend wrote:This is a question that, upon first read, may seem vaguely illogical and abstruse. The key phrase is this: �shorebirds only eat eggs that a crab happens to uncover when it is digging its own nest,� which means that crabs dig their own nest, and thus accidentally uncover the eggs buried of nearby nests, and this is in fact what brings birds, which in turn brings tourists. This provides the link needed for the birdwatcher�s argument; there must be a dense population of crabs for this accidental uncovering to occur; therefore, increasing the space in which crabs can nest will decrease the density, and decrease the number of accidental uncoverings. This is at the heart of the birdwatcher's argument.

However, there is a key assumption in the birdwatcher's argument: increasing the space for crab nesting will ONLY result in a decrease in crab density IF there is not a proportionate increase in crabs. In other words, if there were double the space, AND DOUBLE THE CRABS, the crab density would remain stable. We'd get more accidental egg uncovering, more birds, and more tourists; the birdwatcher would be wrong in her conclusion, and the mayor right.

Answer choice B reflects this logic, explaining that horseshoe crabs are both �prolific� and that their number increases rapidly given favorable circumstances (such as a beach reclamation project to give them extra space).

The other answer choices are mismatches. Choice A is about decreases, not increases, in crab population (and goes by percentage, which means that this situation would not change even if the population did). Choice C is about money, and far out of scope; the argument is about bringing more tourists, not about bringing more tourist money. Choice D is irrelevant and redundant: crabs have more space, so do birds- so what? Choice E discusses an irrelevant fact that has no direct bearing on the situation; we already know that birds stop here to get eggs, so we can safely assume they will continue to do so.

Following the thread of causation (in this case- crab density :arrow: crabs uncovering eggs :arrow: more birds :arrow: more tourists) is key, here and on many CR questions.

Alex
Knewton Verbal Head