Answer : The correct answer for the blank is -
B. nitrogen bases.
DNA (deoxyribonucleic acid) is considered as the genetic material of living organisms and it is passed from one generation to the next generation.
It is composed of sequence of small units, called nucleotide that is primarily made up of three parts-
Nitrogenous base (adenine, thymine, cytosine, and guanine) phosphate group, and deoxyribose sugar.
One living organism is different from another because of the sequence of nucleotides (and thus sequence of nitrogen bases) present in their respective DNA strands.
DNA is first transcribed into mRNA (messenger RNA), which is then converted into particular protein (according to the nucleotide sequence).
The protien is responsible for specific traits in thr organsim.
Thus, option B) is the right answer.
