Which monosaccharide is a component of RNA?

Ribose is the correct answer because it is a five-carbon sugar, specifically an aldopentose, that serves as a fundamental component of ribonucleic acid (RNA). RNA is made up of nucleotides, which consist of a nitrogenous base, a phosphate group, and a ribose sugar. The ribose in RNA connects to the nitrogenous base to form nucleotides, which link together to create the RNA strands that play critical roles in coding, decoding, regulation, and expression of genes.

In contrast, fructose and galactose are both six-carbon sugars (hexoses) that do not participate in the structure of RNA. Fructose is mainly found in fruits and is part of the sugar sucrose, while galactose is a component of lactose. Deoxyribose, although structurally similar to ribose, is a component of deoxyribonucleic acid (DNA), not RNA. Deoxyribose lacks one oxygen atom (specifically, it is missing the hydroxyl group at the 2' carbon), which differentiates it from ribose. Therefore, ribose is uniquely important for RNA structure and function.