People with one sickle cell allele are not likely to get malaria. what is this an example of? artificial selection natural selection gene flow genetic drift

I think the correct answer would be the last option. People with one sickle cell allele are not likely to get malaria. This would be an example of genetic drift. It is one of the mechanism of evolution which involves the change in the frequency of an allele in a certain population due to the random sampling of the organisms. It is when a certain trait is being spread by chance rather by natural selection. Sickle cell is classified as an autosomal recessive disease that is caused by hemoglobin. It is a disease that is inherited depending on how the alleles are received. So, it can be inherited by chance.