Eurasian watermilfoil, a weed not native to Frida Lake, has reproduced prolifically since being accidentally introduced there. In order to eliminate the weed, biologists proposed treating infested parts of the lake with a certain herbicide that is nontoxic for humans and aquatic animals. However, the herbicide might damage populations of certain rare plant species that the lake contains. For this reason local officials rejected the proposal.Which of the following, if true, points out the most serious weakness in the officials' grounds for rejecting the biologists' proposal?
【选项】The continuing spread of Eurasian watermilfoil in Frida Lake threatens to choke out the lake's rare plant species.