The correct answer is b) nucleotides.
Nucleic acids, which include DNA and RNA, are polymers made up of repeating units called nucleotides. Each nucleotide consists of three components: a nitrogenous base, a five-carbon sugar (ribose in RNA and deoxyribose in DNA), and a phosphate group. These nucleotides link together through phosphodiester bonds to form the long chains that make up nucleic acids.
On the other hand, amino acids are the building blocks of proteins, fatty acids are components of lipids, and ribosomes are cellular structures where protein synthesis occurs. Therefore, when it comes to nucleic acids, nucleotides are truly the fundamental building blocks.