The table below shows the quantities of good X a consumer could consume over a 1-week period. Units TOTAL Utility of X 0 - 1 31 2 56 3 75 4 91 5 104 6 115 7 123 8 129 TABLE 6-1 Refer to Table 6-1. If this consumer buys 4 units of X per week, the marginal utility of the 4th unit will be a. 104. b. 16. c. 75. d. 4. e. 91