22. as jose was running down the road, he tripped and his left ankle
twisted violently to the side. when he picked himself up, he
was unable to put any weight on that ankle. the diagnosis was
severe dislocation and sprains of the left ankle. the orthopedic
surgeon stated that she would perform a closed reduction of the
dislocation and attempt ligament repair by using arthroscopy.
(b) what does its
stability depend on? (c) what is a closed reduction? (d) why is
ligament repair necessary? (e) what does arthroscopy entail?
(f) how will the use of this procedure minimize jose's
recuperation time (and suffering)?

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?