If the marginal cost for the state of Montana to increase the speed limit on its interstate highways to 100 mph is estimated to be $500 per day, then Montana should increase the speed limit to 100 mph

A) only if the marginal benefit received each day is less than $500.
B) as long as the marginal benefit received each day is just equal to or greater than $500.
C) as long as the daily marginal cost is lower than it had been before the speed limit increase.
D) unless the marginal benefit received falls to zero.

Answer: B