A weather map shows two areas with a big difference in air pressures. The high air pressure area is to the south, and the low air pressure area is to the north. What do you predict will happen? A) A breeze will blow between north and south.
B) Strong winds will blow from north to south.
C) Strong winds will blow from south to north.
D) Winds will blow back and forth between north and south.

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?