The table below shows the number of foot bones in some horse fossils. Horse Fossil Record Horse Fossil Number of Foot Bones
P 19
Q 17
R 24
S 13

Ancient horses had more bones in their foot then present-day horses. The present-day horse has 11 foot bones. What is the correct order of evolution of the horse starting from the youngest fossil?
Group of answer choices
R P Q S
Q P R S
S R P Q
S Q P R

Number and variety of living organisms includes genetic, species, and ecological types

Which description provides the best objective summary of the article in the passage?

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?