Answer:
Guanine.
Step-by-step explanation:
DNA is the genetic material of almost all the living organisms. DNA contains the nitrogenous bases ( adenine, thymine, cytosine and guanine), deoxyribose sugar and the phosphate group.
The DNA strand are complimentary in nature. The adenine always binds with the thymine with two hydrogen bonds. Guanine binds with cytosine with three hydrogen bonds. The ratio of the pyrimidines is always equal to the ratio of pyrimidines.
Thus, the correct answer is adenine.