smS-l 15. Refer to Figure 3.1. Which of the following would be me st likely to cause the demand for Dr. Pepper to shift from DD to D1? A] an increase in income, assuming that Dr. Pepper is a normal good D} a decrease in the price of TUP. assuming '?UP is a subsn'tute for Dr. Pepper {1) an increase in the price of Dr. Pepper D} an increase in the price of sugar used to make Dr. Pepper