Consider a Mother with Normal Vision Who Has a Son

Multiple Choice

Consider a mother with normal vision who has a son with red-green color blindness. The mother was a "carrier" of the affected gene, as she had a normal phenotype but

A) two recessive alleles.
B) two dominant alleles.
C) one dominant and one recessive allele.
D) a codominant set of alleles.
E) an incompletely penetrating genotype.