Phenylketonuria (PKU) is an autosomal recessive disorder. If a woman who does not have PKU gives birth to a child who has PKU, which of the following men, based on this information alone, could not be the father of the child?
A) a man who has PKU.
B) a man who does not have PKU, none of his siblings or cousins have it, and there was no PKU in his family for six generations before him.
C) a man who does not have PKU but whose mother had PKU.
D) a man who does not have PKU but whose maternal grandmother and paternal grandfather had PKU.
E) Any of these men could be the father of the child.