Match each inheritance pattern with the correct example.

1. a red flower and a white flower creates a pink flower
incomplete dominance
2. two equally dominant genes create type ab blood
sex-linked gene
3. a female carries the gene for color blindness on only one x chromosome
codominance
4. a dog with a genotype of cc has the same phenotype as a dog with a genotype of cc
complete dominance

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?