Step-by-step explanation:
DNA means deoxyribonucleic acid. It is present in all the living beings and it is considered as the main component of chromosomes.
Bases present in a DNA molecule are adenine (A), guanine (G), cytosine (C), and thymine (T).
Also, it is known that adenine will always pair with thymine and vice-versa. Whereas guanine will always pair with cytosine and vice-versa.
Therefore, we can conclude that when two strands of DNA line up, adenine always pairs up with thymine.