You attend a geology lab where you are asked to estimate the age of a fossil. the ratio of parent to daughter elements in the fossil sample is 1: 7. you know that fossils are the remains of living organisms, which have some amount of c-14 isotope. the c-14 isotope, which has a half-life of 5730 years, begins to decay as the organism dies. what would be your estimation of the fossil's age?
a. 2865b. 17,190c. 5730d. 11,460e. 40,110f. 22,920

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?