The correct answer is A. Bases pairs, DNA, Gene, Chromosome, Cell.
Explanation
Nitrogen bases are chemical compounds that compose DNA and RNA, in the case of DNA the bases are adenine, thymine, guanine, and cytosine, while RNA is made up of uracil, adenine, guanine, and cytosine. Additionally, DNA makes up genes, which are structures that store information that is passed on to offspring. Also, genes are organized to form chromosomes (more complex structures) of genetic information. Finally, there are cells, in them are chromosomes, fundamental for the reproduction of an organism. Therefore, the correct answer is A. Bases pairs, DNA, Gene, Chromosome, Cell.