Answer :
Answer: DIRECTIONAL SELECTION; STABILIZING SELECTION.
Explanation: In the United States of America the parasite that causes Malaria is not present,the parasite that causes Malaria are known to be a protozoa of the Plasmodium specie(Plasmodium: P. falciparum, P. malariae, P. ovale and P. vivax.).
DIRECTIONAL SELECTION is also known as positive selection where an advantageous allele increases as a consequence of differences in survival rate and reproduction among different phenotype Population.
STABILISING SELECTION is a type of natural selection in which a trait tend to remain stable,no one trait is felt more.