The nitrogenous bases in a DNA molecule are held together by hydrogen bonds.

These bonds are relatively weak, which is important for DNA's function. The weak nature of hydrogen bonds allows the DNA molecule to easily separate its two strands for replication and transcription.

Here's a breakdown:

* Adenine (A) forms two hydrogen bonds with Thymine (T).

* Guanine (G) forms three hydrogen bonds with Cytosine (C).