What ingredient acts as a leavening agent in baked goods?

The ingredient that serves as a leavening agent in baked goods is baking soda or baking powder. Leavening agents are essential in recipes as they help produce gas bubbles during the baking process. This action causes the dough or batter to rise, resulting in a light and airy texture in the final product.

Baking soda is a chemical leavener that requires an acidic component in the recipe to activate it, while baking powder is a complete leavening agent that contains both the acid and base needed for the reaction. When either of these agents is combined with moisture and heat, they release carbon dioxide gas, which creates the desired rise in baked goods.

Other ingredients, such as sugar, salt, and butter, play vital roles in flavor, texture, and overall structure but do not have the same leavening properties. Sugar can contribute to browning and moisture, salt enhances flavor, and butter provides richness and tenderness. However, none of these ingredients lead to the aeration and rising effect that baking soda and baking powder achieve, making the latter the correct choice in this context.