Many supermarkets and grocery stores offer a choice of "regular" or "organic" produce. Your task is to select two supermarkets and two grocery stores and compare the selection, prices, and apparent quality of organic produce and regular produce. How much more does organic produce cost? Is there any difference in the relative prices of the two types of produce among these supermarkets/stores? Do supermarkets charge a higher price than grocery stores? What are the factors that could explain these differences?