Answer:
Adenine, guanine, cytosine and thymine.
Step-by-step explanation:
The full form of DNA is deoxyribonucleic acid. It is a double-stranded molecule and each strand of DNA is composed of nitrogenous bases, deoxyribose sugar, and phosphate group.
There are four types of nitrogenous bases that are present in DNA. The four bases are adenine, guanine, thymine, and cytosine. Adenine and guanine comes under purine and thymine and cytosine comes under pyrimidine.
Adenine and thymine makes two hydrogen bond with each, guanine and thymine makes three hydrogen bond with each other.