Final answer:
Besides H-bonding, Van der Waals and hydrophobic interactions are primary stabilizing forces in DNA, aiding in the maintenance of DNA's double helix structure.
Step-by-step explanation:
The primary stabilizing forces in DNA, besides hydrogen H-bonding, are Van der Waals interactions and hydrophobic interactions. These forces play a secondary role in DNA stability alongside the hydrogen bonds that are well-known for their role in stabilizing the DNA double helix. Van der Waals interactions contribute to the stabilization between the stacked bases, while hydrophobic interactions help maintain the overall structure of the DNA by keeping the hydrophobic bases in the center of the molecule, away from the aqueous environment.