In a family of four children, all four children have blond hair and blue eyes. which statement best explains why all four children have blue eyes?
a.
all four children are the same gender.
b.
all four children have genes for blue eyes.
c.
all four children have the same type of diet.
d.
all four children are the same height.

The correct answer is option B, All four children have genes for blue eyes.

Explanation:

The allele (representative of any trait) carried by genes expresses themselves at specific locus devise a phenotype. Traits exhibited can be represented by genotype and phenotype of an individual.  

Here in this example, blue colour of eyes is a trait which is common in all the children of the family, this simply signifies that genes carrying the alleles is same in all the children.