Final answer:
The bond that covalently links two DNA nucleotides is the phosphodiester bond, which is formed by a dehydration synthesis reaction and is critical for the stability and integrity of DNA.
Step-by-step explanation:
The phosphodiester bond is the covalent bond that links two DNA nucleotides together in the structure of DNA. This bond is formed through a dehydration synthesis reaction between the hydroxyl group on the 3' carbon of one nucleotide and the phosphate group on the 5' carbon of another nucleotide, which results in the release of a water molecule and the creation of a strong covalent bond between nucleotides, linking them together to form a polynucleotide chain.
Phosphodiester linkages are crucial for the structure and integrity of nucleic acids, providing a backbone that gives DNA its stability and allowing for genetic information to be stored and transmitted. These bonds are responsible for the polymerization of nucleotides into long strands of DNA, and they are what give the DNA molecule its negative charge under physiological conditions. Thus, the correct answer for the bond that covalently links two DNA nucleotides is option b) the phosphodiester bond.