Which of the following indicates that dough is properly proofed?

When determining if dough is properly proofed, a key indicator is that it has doubled in size. This process, known as fermentation, allows the yeast to work by producing carbon dioxide gas, which causes the dough to rise. The ideal proofing time can vary based on several factors such as the temperature and the type of yeast used, but the visual cue of the dough doubling assures that the yeast has activated appropriately and the dough has collected enough air to improve its texture and structure.

In contrast, a dough that is hard to the touch indicates that it may be over-proofed or improperly mixed. If the dough is smaller than its original size, that suggests that it may not have risen adequately due to inadequate proofing or inactive yeast. Lastly, if the dough is cold to the touch, this typically points to under-proofing, as it hasn't had enough time to reach the optimal fermentation temperature and may not have completed its rising process. Thus, the condition of having doubled in size is the most reliable indicator of proper proofing.