13. Refer to Figure 2. Which of the following statement[s] is [are] true? i. At every price, the quantity demanded doubles after the shift from D1 to D2. ii. At every quantity, consumers' willingness to pay doubles after the shift from D1 to D2. iii. Consumers are willing to pay $60 more for the 30th unit after the shift from D1 to D2. 3. Only i] is true. b. Only ii] and iii) are true. c. Only i) and iii) are true. d. All of the above statements are true