Question

the two strands of a dna double helix are held together by ______ that form between pairs of nitrogenous bases. s—s bonds covalent bonds hydrophilic interactions hydrogen bonds ionic bonds

Explanation:

In a DNA double - helix, the two strands are held together by hydrogen bonds between complementary nitrogenous bases (adenine - thymine and guanine - cytosine). S - S bonds are not involved in holding DNA strands together. Covalent bonds form the sugar - phosphate backbone, not the inter - strand connection. Hydrophilic interactions are not the main force holding the two strands of DNA together. Ionic bonds are also not responsible for this.

Answer:

D. hydrogen bonds