Final answer:
Genes contain instructions for assembling proteins, which determine the structure and function of an organism. Hence the correct answer is option A
Step-by-step explanation:
Genes contain instructions for assembling proteins. DNA contains the genes that determine the characteristics of an organism. Proteins are made up of amino acids, and the sequence of amino acids in a protein is determined by the instructions encoded in the genes. So, genes ultimately determine the structure and function of proteins, which in turn impact the traits of an organism.
Hence the correct answer is option A