If the Marginal Costs of 1,2,and 3 Hours of Talking

Multiple Choice

If the marginal costs of 1,2,and 3 hours of talking on the phone are $50,$75,and $105,then the total costs are

A) $50,$150,and $315.
B) $50,$41.67,and $115.
C) $50,125,and $230.
D) $50,$175,and $405.
E) impossible to calculate with information given.