Which of the following is a key component of pastillage?

Pastillage is a type of sugar dough that is primarily used for decorative purposes in pastry work. The key component of pastillage is confectioners' sugar, which serves as the main ingredient providing the structural base for the dough. This fine sugar helps create a smooth, pliable mixture when combined with water and a gelling agent, typically either gelatin or gum arabic.

Confectioners' sugar has a very fine texture that allows for easy rolling and shaping, making it ideal for creating intricate decorations that dry hard and maintain their form. The mixture does not rely on fats or proteins, which would come from ingredients like butter or egg whites; instead, it focuses on sugar and often other stabilizing agents. Therefore, to effectively make pastillage, confectioners' sugar is essential, as it contributes to both the consistency and final texture of the finished product.