Why is it important not to apply ice packs directly to the skin? A. Applying ice directly to the skin won't reduce swelling. B. Applying ice directly to the skin does not decrease pain. C. Applying ice directly to the skin can result in nerve damage. D. Applying ice directly to the skin increases bleeding. Please select the best answer from the choices provided. A B C D

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?