Which red cell typing is most commonly found in the African American donor population?

The most commonly found red cell typing in the African American donor population is Fy(a-b-). This phenotype occurs more frequently among individuals of African descent compared to other populations. The significance of the Fy(a-b-) phenotype lies in the fact that it is associated with the absence of Duffy antigens, which can have implications for blood transfusions and susceptibility to certain infections, as individuals with this phenotype tend to be resistant to malaria due to the lack of Duffy receptors on red blood cells.

In contrast, the other phenotypes listed tend to have lower prevalence rates in the African American population. Lu(a-b-) is related to the Lutheran blood group system, which does not have as high a prevalence in this demographic. Jk(a-b-) is associated with the Kidd blood group system and is also not as common as Fy(a-b-) among African Americans. K-k- relates to the Kell blood group system, with K antigen being more prevalent, while the phenotype K-k- is less frequently observed compared to the Duffy phenotype mentioned.

Overall, the choice of Fy(a-b-) accurately reflects the genetic and immunological characteristics prevalent within the African American donor population, making it the correct answer.