Patty designs an experiment to find out how much water is in an orange. She slices ten oranges, weighs each orange, then dehydrates the slices. When the slices are dry, she again weighs the slices that make up each orange. She puts her data in a table like the following: What data should go in the last column?
A. the difference in weight
B. the size of each orange
C. the number of slices
D. the total weight

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?