In DNA structure, which molecules form the sugar-phosphate backbone of DNA?

• A. Alternating deoxyribose sugars and nitrogenous bases
• B. Alternating ribose sugars and phosphate groups
• C. Alternating deoxyribose sugars and phosphate groups
• D. Alternating nitrogenous bases and phosphate groups

Answer: (C)

Verified step by step guidance

1. Recall the basic structure of DNA, which consists of a long chain of nucleotides.
2. Understand that each nucleotide is composed of three parts: a phosphate group, a sugar molecule, and a nitrogenous base.
3. Identify that the sugar in DNA is deoxyribose, not ribose (which is found in RNA).
4. Recognize that the sugar-phosphate backbone is formed by the alternating connection of phosphate groups and deoxyribose sugars.
5. Note that nitrogenous bases are attached to the sugar molecules and do not form part of the backbone itself.