Nihit wrote:
Mayor: Migrating shorebirds stop at our beach just to feed on horseshoe-crab eggs, a phenomenon that attracts tourists. To bring more tourists, the town council plans to undertake a beach reclamation project to double the area available to crabs for nesting.
Birdwatcher: Without a high density of crabs on a beach, migrating shorebirds will go hungry because shorebirds only eat eggs that a crab happens to uncover when it is digging its own nest.
Which of the following, if true, would provide the mayor with the strongest counter to the birdwatcher’s objection?
A. Every year a certain percentage of crabs are caught by fishermen as bait for eel traps.
B. Horseshoe crabs are so prolific that given favorable circumstances their numbers increase rapidly.
C. On average, tourists who come to the town in order to watch birds spend more money there than tourists who come for other purposes.
D. The additional land made available by the reclamation project will give migrating shorebirds more space.
Some of the migrating shorebirds make only one stop during their migration form South America to Canada
Responding to a pm:
This is what the argument says:
Mayor' plan - Birds come to eat crab eggs at our beach. This brings tourists. So give crabs more area to lay eggs. (With the implication that more crabs may lay more eggs and bring more tourists)
Birdwatcher'a problem with the plan - Crab density should be high i.e. crabs per square foot of area should be more i.e. area should be less. When area is less, more crabs will accidentally uncover other crabs' eggs while digging their own nests. If more area is given to them, they will spread around and hence not uncover each other's nests by mistake. The birds will then not get to eat any eggs and they might stop coming.
Now we want to find the option that counters birdwatcher's problem. i.e. what can the mayor say which will resolve the problem posed by the birdwatcher? How can the mayor ensure more area for crabs and high crab density as well?
B gives you the answer. Crabs are very prolific i.e. if you give them the right conditions, say more space, they will breed more and quickly fill up the space. So even if you increase the area available to them, they will increase their population such that the density of crabs will still remain high. Hence, it is the correct answer.