Answer:
The correct answer will be option D.
Step-by-step explanation:
Genes are the coding sequence of the DNA which codes for specific proteins required for a function.
These genes are present physically as the segments on the DNA. These genes are important to an organism as they control a specific trait like the color of flowers and skin of a human.
The genes are located on a site called "locus' on pair of homologous chromosomes that is one on each chromatid. The number of genes varies from chromosomes that are genes can be present in a large number on a single chromosome.
These genes become functional only after they find a complementary pair on the chromosomes, the reason parents need to donate their genes during fertilization.
Thus, option D is the correct answer.