The correct answer is option 3, Eucalyptus. Eucalyptus trees are often referred to as ‘Green Gold’ because they grow quickly and can be harvested for timber and paper production. However, they are considered an ecological disaster in many areas. Eucalyptus trees have a high water demand and can deplete local water resources, leading to water scarcity for other plants and animals. They also release a chemical called allelopathic, which inhibits the growth of other plant species nearby, causing a decrease in biodiversity. In addition, eucalyptus trees are invasive species in some regions, outcompeting native vegetation and disrupting local ecosystems. Therefore, while the eucalyptus tree may offer economic benefits, it can have negative environmental impacts, earning it the title of an ecological disaster.