c. icing sugar

Icing sugar, also known as powdered sugar, confectioners' sugar, or icing powder, is refined granulated sucrose ground into an extremely fine powder. The production process involves pulverizing white granulated sugar to a consistency fine enough to dissolve quickly in minimal liquid, resulting in a texture resembling flour or talc. A small percentage of anti-caking agent—typically cornstarch or silica—is added to prevent clumping and moisture absorption during storage. The result is a pure white, free-flowing powder with negligible flavor beyond sweetness, designed for applications requiring smooth texture and rapid incorporation into frostings, glazes, and dusted finishes.

Icing sugar is the primary ingredient for royal icing, buttercream frostings, fondant, and other cake decorations requiring a smooth, lump-free finish. It is widely used for dusting finished baked goods, pastries, and desserts for visual appeal and sweetness. In confectionery, it serves as a binding agent in glazes for cookies and petit fours. The powder's fine particle size allows it to dissolve quickly in minimal liquid, making it ideal for creating silky icings without grittiness. It is less suitable for applications requiring caramelization or where granular texture is desired.