What role does yeast play in baking?

Yeast plays a crucial role in baking primarily through the process of fermentation. When yeast is added to dough, it consumes sugars present in the flour and converts them into carbon dioxide and alcohol through fermentation. The production of carbon dioxide gas causes the dough to rise, creating air pockets that result in a light and airy texture in the finished product. This leavening action is fundamental to many baked goods, including bread, rolls, and certain pastries, as it contributes to their desirable volume and softness.

While yeast may impart some flavor to the bread through the byproducts of fermentation, its primary function is not as a flavor enhancer. Additionally, yeast does not act as a preservative in baked goods; preservatives are typically other ingredients added to extend shelf life. Furthermore, yeast does not thicken dough; rather, it allows the dough to expand and become more pliable by introducing gas bubbles throughout the mixture. Thus, the fermentation process is what primarily defines the role of yeast in baking, making the understanding of option C essential.