Some species in the weasel family, such as skunks, protect themselves by spraying a foul-smelling musk oil when threatened. why would a spray defense be a useful mechanism for a species? a) predators would confuse the species with others that produce foul smells. b) spray can turn a predator away before an individual is harmed. c) it is hard for other species to mimic a spraying defense. d) there is no known defense against foul-smelling sprays.

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?