what makes the kingdom Protista unique?

Protists are not made of cells
Protists share a common ancestor with fungi only
Protists are single celled
Protists do not share a common ancestor

The correct answer is:

Protists are single-celled eukaryotic organisms that are not classified as plants, animals, or fungi. They are a highly diverse group that includes a wide range of organisms with very different characteristics. This makes the kingdom Protista unique in the sense that it encompasses a vast array of organisms that do not fit neatly into the established categories of plant, animal, or fungi.