What is the key structural difference between deoxynucleotides and dideoxynucleotides?

• A. Dideoxynucleotides lack a 2' hydroxyl group
• B. Deoxynucleotides have a double bond at the phosphate group
• C. Deoxynucleotides contain an extra nitrogenous base
• D. Dideoxynucleotides lack a 3' hydroxyl group

Answer: (D)