Which of the following is the repeating structural unit that forms RNA and DNA?

• A. Nucleotide
• B. Amino acid
• C. Fatty acid
• D. Monosaccharide

Answer: (A)

Verified step by step guidance

1. Understand that DNA and RNA are nucleic acids, which are polymers made up of smaller repeating units.
2. Recall that the basic building blocks of nucleic acids are called nucleotides, each consisting of a sugar, a phosphate group, and a nitrogenous base.
3. Recognize that amino acids are the building blocks of proteins, not nucleic acids.
4. Know that fatty acids are components of lipids, and monosaccharides are simple sugars, neither of which form the structural units of DNA or RNA.
5. Conclude that the repeating structural unit forming both DNA and RNA is the nucleotide.