After a tree falls in the forest, it slowly decays until it eventually becomes part of the forest floor. many organisms are involved in this decomposition, what is an example of a microorganism that aids in this process? a) mold is a beneficial microorganism that can aid decomposition. b) mice are beneficial microorganisms that can aid decomposition. c) beetles are beneficial microorganisms that can aid decomposition. d) vultures are beneficial microorganisms that can aid decomposition.

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?