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

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

A) $50, $150, and $315 respectively.
B) $50, $41.67, and $115 respectively.
C) $50, $125, and $230 respectively.
D) $50, $175, and $405 respectively.