Answer:
Parasitism.
Step-by-step explanation:
Parasitism is the relationship that is present between Plasmodium and humans because one organism takes benefit from the other whereas the other get harmed by the other. In Plasmodium and humans relationship, human gets harmed from the mosquito by having malarial disease, while on the other hand, mosquito is benefitted by sucking of blood which is a food source for mosquitoes.