* Adenine (A) with Thymine (T)

* Guanine (G) with Cytosine (C)

These pairs are held together by hydrogen bonds. Adenine and thymine form two hydrogen bonds, while guanine and cytosine form three hydrogen bonds. This specific pairing is called complementary base pairing.

It's important to remember that this pairing applies to DNA. In RNA, thymine is replaced by uracil (U), so the pairings are:

* Adenine (A) with Uracil (U)

* Guanine (G) with Cytosine (C)