Answer: Hydrogen bonds
Explanation: A hydrogen bond is a weak intermolecular force of attraction between the positive and negative poles two charged atoms. Hydrogen bonds occur when hydrogen atoms covalently bond to atoms of very highly electronegative elements such as oxygen, nitrogen. In DNA, hydrogen bonds between the bases hold the two DNA strands together. In DNA, Adenine forms two hydrogen bonds with Thymine while Guanine forms three hydrogen bonds with Cytosine.
