the terai region of southern nepal is known for high rates of malaria, a disease caused by a parasite transmitted by mosquitos. the parasite causes severe anemia by infecting red blood cells. two groups of people live in terai: the tharus people who are native to the region, and non-tharus people who have migrated to the region in the last several decades. native tharus people have a significantly lower rate of malarial infection than the non-native people living in terai. of the hypotheses listed below, which is the most probable?
