Aline is drawn through (–4, 3) and (4, 3). which describes whether or not the line represents a direct variation? the line represents a direct variation because   -4\3 =4\3the line represents a direct variation because it is horizontal. the line does not represent a direct variation because it does not go through the origin. the line does not represent a direct variation because –4(3) ≠  4(3).

Astudy by solloch and et. al., in 2017, gives the map above which shows the frequency of alleles with a ccr5-delta32 mutations over 87 different countries. this mutation deletes the presence of a co-receptor (ccr5) on the outside of human t-cells (lymphocytes). some viruses, such as the one responsible for the black death and human immunodeficiency virus (hiv), require this receptor for attachment to host cells during the infection process. the black death was an epidemic that passed over northern europe during the 14th century killing nearly 60% of europeans. according to this information, which explanation best explains why northern europeans show a greater immunity for hiv than some other parts of the world?