Question

which part of the image below is the backbone of dna?

Explanation:

DNA's backbone is composed of alternating sugar (deoxyribose) and phosphate groups. In the given diagram, the phosphate group is labeled as 1 and the sugar as 2. Together, these two components form the backbone. The nitrogenous base (labeled 3) is not part of the backbone but pairs with bases on the complementary DNA strand.

Answer:

1 (Phosphate group) and 2 (Sugar) together form the backbone of DNA.