When a DNA molecule replicates, a. The hydrogen bonds along the sugar-phosphate chain are broken. b. The covalent bonds along the sugar-phosphate chain are broken. c. The hydrogen bonds between the nitrogenous base pairs are broken. d. The covalent bonds between the nitrogenous base pairs are broken.
The DNA chain breaks the hydrogen bonds between nitrogenous bases when it replicates so that the bases are exposed to DNA polymerase. Breaking the backbone would ruin the molecule.