A graph of price versus quantity shows two parallel supply curves. Each is a straight line ascending from lower left to upper right. From left to right the curves are S and S prime. Note that curve S originates at the origin. Refer to Figure 4-6. The shift from S' to S in the market for chocolate cake could be caused by a. a decrease in the number of commercial bakers. b. a decrease in the price of chocolate cake. c. a decrease in the price of butter. d. an improvement in oven technology