Due to climate change in recent years, the flower rhododendrons that originally lived in the deep mountains of the Qinling Mountains in the spring and summer gradually migrated to the Greater Xing'an Mountains in Northeast China. Just as the flower rhododendrons multiplied in the Greater Xing'an Mountains, the number of willow warblers was greatly reduced. The willow warbler is completely different, so the large decrease in the willow warbler has nothing to do with the large increase in the flower rhododendron. Which of the following, if correct, would weaken the above conclusion most? ['All kinds of forest pests are the food of cuckoo flowers, and the only food of willow warbler is pine caterpillar.', 'The flower rhododendron does not have a nesting instinct. In order to breed the offspring flower rhododendron, the egg can only be laid in the willow warbler nest.', "Willow warbler and flower rhododendron both feed on forest pests, but flower rhododendrons do not eat willow warbler's main food, pine caterpillars.", "Baby Rhododendron can only be hatched in willow warbler's nest."]