Watanabe: To protect the native kokanee salmon in the lake, we must allow fishing of native trout. Each mature trout eats about 250 mature kokanee annually. Lopez: The real problem is mysis shrimp, which were originally introduced into the lake as food for mature kokanee; but mysis eat plankton -- young kokanees' food. The young kokanee are starving to death. So eradicating the shrimp is preferable to allowing trout fishing. Which one of the following principles, if valid, most strongly supports Lopez's conclusion? ['When seeking to increase the population of a given species, it is most important that one preserve the members of the species who are in the prime reproductive stage of their lives.', 'When trying to protect the food supply of a particular species, it is best to encourage the method that will have the quickest results, all else being equal.', 'No non-native species should be introduced into a habitat unless all the potential effects of that introduction have been considered.', 'Eliminating a non-native species from a habitat in which it threatens a native species is preferable to any other method of protecting the threatened native species.']