Table 10-2 Quantity of Soup (cups) Total Utility Quantity of Sandwiches Total Utility 1 40 1 45 2 60 2 75 3 72 3 102 4 82 4 120 5 88 5 135 6 90 6 145 Table 10-2 above shows Keira's utility from soup and sandwiches. The price of soup is $2 per cup and the price of a sandwich is $3. Keira has $18 to spend on these two goods. Refer to Table 10-2. What is Keira's marginal utility per dollar spent on the third cup of soup? A) 72 units of utility B) 36 units of utility C) 12 units of utility D) 6 units of utility