The Total Utility You Get from Eating Slices of Pizza

The total utility you get from eating slices of pizza on a given night is the

A) marginal utility of the last slice times the total number of slices eaten.
B) sum of the differences in marginal utility as you increase the number of slices eaten.
C) sum of the marginal utilities of all slices eaten.
D) sum of the marginal utilities per dollar spent on all slices eaten.