According to the IUCN, the total number of plant and animal species is about:-

1.5 million

The correct answer is Option (1) → 1.5 million

IUCN is the world’s oldest and largest global environmental organization. Known for maintaining the IUCN Red List, which assesses the conservation status of plant and animal species. According to the International Union for Conservation of Nature and Natural Resources (IUCN) (2004), the total number of plant and animal species described so far is slightly more than 1.5 million, but we have no clear idea of how many species are yet to be discovered and described.