X linked recessive there can never be any Male to Male transfer since the male offspring gets Y from father. the pedigree shows Male to Male transmission so this cannot be X linked recessive
My understanding is that if parents are unrelated by blood to those affected, we assume that they are not carriers (in the recessive case). Therefore, if we have a male father affected with x-linked recessive married to a non-carrier, there's no way any of his offspring would be affected.
"If one parent is not a carrier, then a child can only inherit a disease allele from the other parent. In these problems, we can assume that any individual marrying into the family is not a carrier."
The point here is, they are asking us to eliminate the only answer that is not possible. I got it wrong. read well fellas