Official Explanation

Evaluation of a Plan

In hopes of preventing the nonnative species northern snakehead from eliminating rare native fish species, wildlife officials have for the last three years been paying recreational fishers for each snakehead they catch. The northern snakehead has no predators in the area.

This question requires us to identify information that would be useful for determining whether the officials' plan will succeed.

Note that the plan has already been in effect. Nevertheless, we are given no information as to how well the plan has succeeded so far. To determine whether it is responsible to keep paying these fishers to catch northern snakehead, it is vital to understand whether the fishers' work up to this point has had any observable effect.

That is, it would be helpful to anyone who wants to determine whether the officials' plan is likely to succeed to have information about how the numbers of rare native fish species have been changing during that time.

A. This information would be useful for determining whether there may be alternative ways of reducing the northern snakehead population. However, it is not useful for determining whether the plan in question is likely to be successful.

B. Correct. As noted above, this information would be helpful in assessing whether the officials' plan is likely to succeed. If the numbers of rare native fish species have stayed constant or even declined throughout the period that the plan has been in place, it seems unlikely that the plan will ultimately be successful.

C. This information may provide a small amount of information as to how great a threat the northern snakehead might pose, but not much. For one thing, in its native region, the snakehead likely preys on different species from those in the region in question. More importantly, however, is the fact that this information is simply not useful to determining whether the officials' plan is likely to work in the region in question.

D. This might be useful for determining whether fishers have been motivated by the plan. This could potentially be useful for determining whether the plan will work; after all, the plan will not likely work if very few northern snakeheads are actually removed. Nevertheless, it is not as useful as noting the changes in the native fish population since the plan first went into effect.

E. Determining whether there are other threats to the rare native fish species would tell us whether the plan, if successful, is sufficient to save the rare fish species. Still, it is not useful in determining whether that plan is likely to be successful.

The correct answer is B.