The correct option is A Plasmodium
Plasmodium is a large genus of parasitic Protozoa. The parasitic stages infect the red blood cells of the blood and so are intra-cellular.
Ancylostoma is a species of hookworm. It is an intestinal parasite of domestic cats and dogs.
Mosquito are midge-like flies and Entamoeba is a genus of Amoebozoa, found as internal parasites of animals.