Name the class of nutrients to which sugars and starches belong?

Sugars and starches are carbohydrates. Carbohydrates may be simple or complex.

Simple carbohydrates, or simple sugars, include monosaccharides (e.g., glucose, fructose, galactose, xylose and ribose) and disaccharides (e.g., sucrose, lactose and maltose). They consiste of one (mono) or two (di) sugar molecules.

Complex carbohydrates, or complex sugars, include oligosaccharides (e.g., fructo-oligosaccharides [FOS], galactooligosaccharides [GOS] and mannan oligosaccharides [MOS]) and polysaccharides (e.g., starches, pectins, and cellulose). They consist of a few (oligo) or many (poly) sugar molecules.