Answer:
The correct answer is - A covalent bond between a phosphate group and two 5-carbon ring carbohydrates over two ester bonds.
Step-by-step explanation:
A bond between a 5 carbon sugar and a phosphate group makes the sugar-phosphate-sugar backbone in nucleic acids. A diester bond links two different nucleotides together to form a polynucleotide.
These are the strong covalent bonds that links a 3' carbon atom of one sugar molecule and the 5' carbon atom of another in deoxyribose sugar in DNA and ribose sugar in RNA.