Answer: The correct answer for the fill in the blank is D) Passing of traits from parents to children.
Heredity can be defined as the passing of traits from one generation to the next generation. These traits can be the mental or physical characteristics of the parent. The traits are passed to the offsprings in the form of genetic material, which is DNA ( deoxyribonucleic acid) in most of the life forms.
Example- The genes ( segment of DNA, which code for specific proteins) for green eyes are passed from parent to child. This gives green eye color to the child.
Thus, the correct answer is Heredity refers to the passing of traits from parents to children