Based on the red cell phenotyping results, what conclusion can be drawn regarding paternity?

The conclusion that paternity may be excluded on the basis of Rh typing is correct because the Rh factor, which indicates the presence or absence of the D antigen on red blood cells, is a critical component in determining biological relationships. If a child has a specific Rh factor that is incompatible with the alleged father's Rh factor, it can suggest that he is not the biological father.

Rh typing alone can sometimes provide sufficient information for exclusion, particularly if the mother is known to be Rh negative. If the child is Rh positive, and the alleged father is Rh negative, it is biologically impossible for him to be the father because an Rh negative father cannot pass on the D antigen. This exclusion can thus support claims of non-paternity in cases where the child’s Rh determination conflicts with that of the father.

In contrast, while ABO typing can also be useful, it is typically less definitive. The ABO blood group system can sometimes allow for multiple compatible parental combinations, making it less conclusive when trying to confirm or exclude paternity based solely on ABO group results. Therefore, Rh typing provides a clearer pathway to exclusion when discrepancies arise.