Given the typing results Le(a-b-); Fy(a-b-); Js(a+b+), which racial ethnicity does this donor most likely belong to?

The typing results indicate a specific set of blood group phenotypes that can offer insight into the donor's likely racial or ethnic background. In particular, the Le(a-b-), Fy(a-b-), and Js(a+b+) phenotypes present in this scenario suggest a predisposition commonly found in individuals of African descent.

The Lewis blood group system shows that individuals with the Le(a-b-) phenotype are often found at a higher frequency in African populations compared to other ethnic groups. Similarly, the absence of the Fy(a) and Fy(b) antigens, indicated by Fy(a-b-), is also notably more common in individuals with African ancestry, as these antigens are typically more prevalent among Caucasian and Asian populations. Lastly, the Js(a+b+) phenotype is frequently observed in African Americans, adding further evidence to support this association.

Collectively, these blood group typings provide a compelling case for the donor's likely connection to the African American population, making it the most probable answer among the options provided.