If night blindness is a recessive trait what should the phenotype of the couple's fourth child be?

If night blindness is a recessive trait, the couple's fourth child will exhibit the phenotype associated with night blindness only if both parents carry the recessive allele (i.e., they are either carriers or affected). If at least one parent has the dominant allele for normal vision, the child will not express night blindness. Therefore, the phenotype of the fourth child could be either normal vision or night blindness, depending on the genetic makeup of the parents.