Which of the following represents a direct exclusion in paternity testing?

In paternity testing, a direct exclusion occurs when the genetic makeup of a child cannot be reconciled with that of a potential father based on their blood type or genetic markers. The correct answer, represented by a group of blood types that includes Fy(a+b+) Fy(a+b-) and Fy(a+b-), demonstrates a situation where the combination of the child’s phenotype and the alleged father's phenotype indicates that paternity is impossible.

In this case, the presence of specific antigens in the child's phenotype directly contradicts the expected antigens from the alleged father’s genotype. For instance, if the child has the Fy(a+b+) phenotype, but the alleged father can only pass down a Fy(a+b-) phenotype, then he cannot be the biological father, resulting in a direct exclusion of paternity.

In contrast, other options do not directly indicate an exclusion. For example, the blood types in the first option involve possible ABO types that could align with a father's type, leading to potential inclusion rather than direct exclusion. The other choices feature different combinations of blood types or antigens that do not facilitate a clear-cut disqualification of paternity. Therefore, the choice that shows a direct incompatibility in genetic testing due to the antigens involved represents a clear and