DNA and RNA do not differ from each other in which of the following

Nature of the backbone

The correct answer is Option (3) → Nature of the backbone
DNA and RNA do not differ from each other in the nature of the backbone.

Reasoning:

• Nature of sugar → Different (DNA has deoxyribose, RNA has ribose).

• Nature of nitrogenous bases → Different (DNA has thymine, RNA has uracil).

• Secondary structure → Different (DNA is double-stranded helix, RNA is usually single-stranded).

• Nature of the backbone → Same in both: a sugar–phosphate backbone.