Which of these is a difference between a DNA and an RNA molecule?

Question

DNA is usually double-stranded, whereas RNA is usually single-stranded.
DNA contains uracil, whereas RNA contains thymine.
DNA contains nitrogenous bases, whereas RNA contains phosphate groups.
DNA contains five-carbon sugars, whereas RNA contains six-carbon sugars.
DNA is a polymer composed of nucleotides, whereas RNA is a polymer composed of nucleic acids.

Answer 1

The correct difference between a DNA and an RNA molecule from your options is:

DNA is usually double-stranded, whereas RNA is usually single-stranded.

The other statements are incorrect:

• DNA contains thymine, whereas RNA contains uracil.
• Both DNA and RNA contain nitrogenous bases and phosphate groups.
• DNA contains deoxyribose (a five-carbon sugar), while RNA contains ribose (also a five-carbon sugar, not six).
• Both DNA and RNA are polymers made up of nucleotides, not DNA composed of nucleotides and RNA composed of nucleic acids.