Understand the basic structure of nucleic acids: DNA and RNA are both nucleic acids composed of long chains of nucleotides.
Recognize that nucleotides are the building blocks of both DNA and RNA. Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.
Identify the differences in the sugar component: DNA contains deoxyribose, while RNA contains ribose.
Note the differences in nitrogenous bases: DNA uses adenine, thymine, cytosine, and guanine, whereas RNA uses adenine, uracil, cytosine, and guanine.
Conclude that despite these differences, the fundamental similarity is that both DNA and RNA are composed of nucleotides, which is the correct answer to the problem.