Which of the following best describes nucleotides?

Nucleotides are indeed best described as the building blocks of nucleic acids. They are organic molecules that consist of three components: a phosphate group, a five-carbon sugar (which can be ribose or deoxyribose), and a nitrogenous base (which can be adenine, thymine, cytosine, guanine, or uracil).

These components come together to form nucleotides, which link together through phosphodiester bonds to create the long chains known as nucleic acids—DNA and RNA. These nucleic acids play essential roles in storing and transmitting genetic information, as well as in the synthesis of proteins.

In understanding the other options, it's clear they pertain to different biological macromolecules. Sugars are carbohydrates, and while they can be linked to nucleotide structures (as ribose or deoxyribose sugars), nucleotides themselves are not building blocks of sugars. Proteins are formed from amino acids, not nucleotides. Fatty acids, being components of lipids, have no direct connection to the structure or function of nucleotides. This context emphasizes that nucleotides are specifically associated with nucleic acids, establishing the solid foundation for the correct choice.