The author's goal here is to obtain an accurate count of seabirds killed by fishing nets. The plan is to offer something that the fishing industry needs, which is toxin testing. Ideally, this will encourage them to turn in bird carcasses, thus revealing the amount of birds that were killed.
We want to show that this plan will not succeed.
B is correct, because the fishing industry will get what it wants, without offering an accurate count in return. If they can get the information that they need with just a few birds, they are not going to hand over every bird carcass. Remember, they have an interest in not doing so.