Which base is found only in DNA?

adenine

The base found exclusively in DNA is thymine.

Thymine is pyrimidine. A pyrimidine is a base that contains a single ring form. It is constructed of a specific nitrogenous base that serves as its basic foundation. it also contains one phosphate group and one deoxyribose sugar molecule to complete its structure.

Thymine serves as main the main stabilizer of the entire group of bases in DNA. It will always bind to a purine called adenine. A purine is a base that contains a double ring form. When these two bind together, a double hydrogen bond is formed.

Thymine is never found in RNA, rather it is replaced by Uracil.