Endangered species are living organisms whose population sizes have declined to critical levels, putting them at risk of extinction. (18) _______ when their populations have decreased to such a degree that they are likely to disappear entirely from their natural habitats if (19) _______ are not implemented.

     The International Union for Conservation of Nature (IUCN) is responsible for classifying species as endangered or critically endangered based on criteria such as population size, (20) _______ , and geographic range. The loss of endangered species can significantly impact the ecosystem, (21) _______ .

     Endangered species play a vital role in maintaining the ecological balance of our planet. They provide (22) _______ such as pollination, seed dispersal, and regulating the population of other organisms in the food chain. They also have important medicinal, cultural, (23) _______

     Protecting endangered species is therefore crucial in ensuring these services are preserved for future generations. Additionally, conservation efforts protecting endangered species can lead to the conservation of other species and their habitats, ultimately contributing to the overall health and stability of the ecosystem.

Mark the letter A, B, C, or D on your answer sheet to indicate the correct option that best fits each of the numbered blanks from 18 to 23.