The economy around Lake Paqua depends on fishing of the lake' s landlocked salmon population. In recent years, scarcity of food for salmon there has caused a decline in both the number and the size of the adult salmon in the lake. As a result, the region' s revenues from salmon fishing have declined significantly. To remedy this situation, officials plan to introduce shrimp, which can serve as a food source for adult salmon, into Lake Paqua. Which of the following, if true, most seriously calls into question the plan's chances for success? ['Salmon is not a popular food among residents of the Lake Paqua region.', 'The shrimp to be introduced into Lake Paqua are of a variety that is too small to be harvested for human consumption.', 'The primary food for both shrimp and juvenile salmon is plankton, which is not abundant in Lake Paqua.', 'Fishing regulations prohibit people from keeping any salmon they have caught in Lake Paqua that are smaller than a certain minimum size.']