The kingdom, Protista, includes

The kingdom Protista includes all organisms -unicellular or multicellular- that lack classification in the animal, plant or fungi kingdoms.

Explanation:

Protista is a heterogeneous group of eukaryotic organisms that is divided into several groups, according to their morphological and functional characteristics.

This kingdom include unicellular and multicellular organisms -autotrophic or heterotrophic- in which the genetic lineage of each group is not very clear, although a common ancestor and the existence of parallel evolution (paraphyletic) can be determined.

The groups into which the Protista kingdom is divided are:

Protists are said to be a heterogeneous group since no common characteristics have been identified among these different groups that could serve as a basis for defining them as a single whole.

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Characteristics of the protists link

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.