Answer:
The correct answer would be the order of the codons.
The nucleotide sequence of DNA (deoxiribonucleic acid) is the main factor which makes organisms different from each other.
This sequence is decoded into the codon sequence of mRNA (messenger RNA) which ultimately decides the amino acid sequence of a polypeptide.
This protein decides the phenotype of an organism. Different phenotype (like skin color, eye color, tall and short) make organisms different from each other.
Thus, we can say that order of the codons makes organisms different from one another.