Homework need help‍♀️.

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.

*will mark brainliest to the first and correct answer less species diversity results in less a. oxygen b. food c. drinkable water d. all of the above

Free brainliest! what is a characteistic of the american stradfordshire?