Which of the following groups does the IUCN Red List use to classify species according to the likelihood that they will become extinct?
i. Extinct and Threatened species.

ii. Endangered and Vulnerable species.

iii. Vulnerable, Extinct and Threatened species.

iv. Threatened, Vulnerable, Endangered and Extinct species.

The IUCN Red List of Threatened Species sometimes referred to as the IUCN Red Data Book, is a thorough evaluation of the conservation status of many species, subspecies, and variations of plants, animals, and fungi on a global scale. It is largely regarded as the most reliable and thorough information source on the status, ecology, and distribution of the world's species, and it is an essential tool for efforts around the world to conserve and manage wildlife. Based on a set of factors such as population size, the pace of decline, and distribution, the IUCN Red List divides species into various threat categories, including "Extinct," "Critically Endangered," "Endangered," "Vulnerable," "Near Threatened," and "Least Concern."