An organism has the following characteristics: cell wall, autotrophic, unicellular, and eukaryotic. What kingdom does it most likely belong in?

A eukaryotic organism has cells with a nucleus, which rules out Eubacteria. It is unicellular, so it is unlikely to be classified in Plantae, whose members are generally multicellular. Some protists, such as algae, are unicellular autotrophs with cell walls, so Protista is the best fit.

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