Which of the following is true concerning the balance between the solar energy absorbed and radiated by earth? a. earth’s atmosphere absorbs a larger fraction of total solar energy than it radiates. b. more than 90% of the solar energy that strikes earth is absorbed. c. earth’s surface is responsible for absorbing a larger fraction of energy than it radiates. d. none of the above.

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?