What does not belong South America Africa Australia or Antarctica?

Australia does not belong in the group of South America, Africa, and Antarctica because it is the only continent that is primarily an island and is entirely located in the Southern Hemisphere, while South America, Africa, and Antarctica are all connected to the landmasses of the Americas and Eurasia/Africa. Additionally, Australia is known for its distinct ecosystems and species, which are different from those found on the other continents.