Final answer:
Bags of bread shouldn't be stacked primarily because the pressure can cause the bread to flatten and become misshapen, which affects its quality. While accessibility and safety are also considerations, they are secondary to maintaining the bread's integrity.
Step-by-step explanation:
The question "Why don't we allow bags of bread to be stacked on top of each other primarily?" primarily concerns the proper storage and handling of bread to maintain its quality. The most accurate answer is 1) Because it will cause the bread to flatten and become misshapen. Stacking bags of bread can apply pressure on the loaves at the bottom, which can lead to the bread being squished and losing its intended texture and shape. This is especially true for bread that is light and fluffy as a result of the action of yeast on sugar, which creates air pockets that make the bread rise, as described in the provided references that discuss yeast's role in the rising process of bread. Answer 2) and 4) are also considerations; however, they are secondary to the primary concern of maintaining the bread's shape and texture. Difficulty accessing the bread and potential safety hazards do not primarily relate to the aspect of the bread quality being compromised due to stacking. Answer 3) is less relevant as stacking, in and of itself, does not directly cause bread to spoil faster. Other factors like temperature and moisture have a greater impact on the shelf-life of bread.