protists in the genus plasmodium must live in host cells and harm their host cells providing an example of a relationship but what kind of relationship

Parasitism

Explanation:

Parasitism is a negative interaction between the two organisms of different species. Here, a heterotrophic organism derives nutrition and/or other benefits from the living tissues of another organism. The organism that is benefited, mostly in terms of nutrition is called parasite and the other one which is harmed is called the host. In the given example, the parasite Plasmodium lives in the host cells and harm the host cells. Since Plasmodium is benefited while the host cells are harmed, it is an example of parasitism.

Answer: Parasitism relationship