"Fifty percent of cut roses sold in February are sold on Valentine's Day. On Valentine's Day in a recent year, the price of a dozen roses jumped from $8.00 to $19.99 at one local store in Chicago. Another bestseller on Valentine's Day is candy. About 13 percent of the annual sales of candy take place on Valentine's Day. Yet the price of a box of chocolates increases modestly if at all on this holiday."Can you explain why this happens?