Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Individual nucleotides can be linked together through their phosphate groups to form nucleic acid polymers. Once constructed, DNA generally exists as two strands that are linked together by hydrogen bonds, producing a double-helical structure (see Figure below ). Answer: nucleic acid polymers
Output:
Individual nucleotides can be linked together through their phosphate groups to form?