What is sourdough?

Sourdough is defined as naturally fermented dough, which is the correct choice. This type of bread relies on wild yeast and lactic acid bacteria present in the environment to ferment the dough. The process begins by creating a starter, a culture of flour and water that captures these microorganisms over time. As the starter ferments, the wild yeast naturally present in the air or the flour feeds on the sugars in the dough, producing carbon dioxide and lactic acid.

This fermentation process not only helps the dough rise but also imparts a distinct tangy flavor and chewy texture that is characteristic of sourdough bread. Unlike yeast-risen bread, which typically uses commercial yeast for leavening, sourdough's unique taste and texture arise from the natural fermentation process and the specific strains of microorganisms involved.

While the other options mention different types of bread, they do not capture the essence of what makes sourdough unique. Yeast-risen bread relies on commercial yeast, quick breads are made using baking powder or baking soda for rapid leavening, and flatbreads are typically unleavened or use minimal leavening agents. Thus, naturally fermented dough accurately describes the primary characteristic of sourdough.