Which kingdom forms a link between prokaryotes and complex eukaryotes?

Question: Which kingdom forms a link between prokaryotes and complex eukaryotes?

The kingdom that forms a link between prokaryotes and complex eukaryotes is the kingdom Protista. Protists are unicellular eukaryotes that exhibit a wide range of morphological, physiological, and ecological diversity. Some protists are similar to prokaryotes in their small size and simple structure, while others are more complex and share some characteristics with plants, animals, or fungi. Some protists have evolved specialized structures and processes that are similar to those found in more complex eukaryotes, such as cilia, flagella, and the ability to perform photosynthesis. The diversity of protists makes them an important group for understanding the evolution of eukaryotes, and they have been studied extensively by microbiologists, ecologists, and evolutionary biologists.