Whats number 18? A and B

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

Explain how ancient whale fossils found in eqypt are believed to support the theory of evolution.

Match each term to its best definition? sedimentary depositional enviornment