Which individual would provide saliva that most effectively neutralizes Leb antibodies?

The most effective neutralization of Leb antibodies is associated with individuals who possess the Le (Lewis) gene and express the Se (secretor) gene. Option C describes an individual who is Le (Lewis positive) and Se (secretor positive).

In this context, Lewis antigen expression is crucial. Individuals with the Le gene produce Lewis antigens in their saliva, which can effectively neutralize antibodies specific to the Leb antigen. Coupled with the Se gene, which allows for the secretion of these Lewis antigens into bodily fluids like saliva, individuals who are Le H Se can produce a significant quantity of Leb antigen in their saliva. This means their saliva will contain more neutralizing factors for Leb antibodies as compared to individuals lacking either the Le or Se genes.

The other options represent variations of Lewis and secretor phenotypes that would not express the combination of both necessary factors as effectively as the Le H Se genotype, leading to a reduced capacity to neutralize Leb antibodies.