Answer:
A. red blood cells containing malaria
Step-by-step explanation:
Malaria is a disease-causing pathogen in humans. It is caused by species of the parasite Plasmodium sp., which is transmitted as sporozoites by the Anopheles mosquito upon biting the host. These travel through the bloodstream to the liver where they mature into merozoites. These reenter the bloodstream and mature into trophozoites and schizonts that produce more merozoites.
When they multiply within the red blood cell, they burst the red blood cell open, and go on to infect other cells. This infection's symptoms are cyclic and include high fever, chills and other flu-like symptoms.
Malaria is a deadly illness, causing harm to its hosts, and in many cases death. Thus, this cannot be defined as symbiosis, which is typically beneficial to both organisms.