Identify the primary function of baking soda in baking.

Baking soda's primary function in baking is to act as a leavening agent. It works by creating carbon dioxide gas when it reacts with acidic ingredients present in the dough or batter. This gas gets trapped in the mixture, causing it to expand and rise, which results in a light and airy texture in the final product.

The reaction occurs almost immediately upon mixing the ingredients, so it’s essential to bake the goods shortly after they've been mixed to take full advantage of this leavening effect. Common acidic ingredients that activate baking soda include buttermilk, vinegar, lemon juice, and yogurt. This is crucial for recipes like cookies, pancakes, and quick breads, where a tender texture is desired.

The other options listed do not accurately describe the primary function of baking soda: it does not add flavor, provide color, or preserve freshness in baked goods. Its role is strictly related to the leavening process, making it an essential ingredient in many baking recipes.