The correct order of heredity structures from least to most complex is codon, gene, DNA, and chromosome. A codon is a basic unit of genetic information, whereas chromosomes are larger structures that house many genes. Understanding this organization is key in the study of genetics. ;
The correct order of heredity structures from least to most complex is codon, gene, DNA, and chromosome. This hierarchy establishes a foundation for understanding genetic organization. Thus, the correct option is A.
;