A. This is the increase in revenue when the workers move from 10 to 11.
B. This is the total marginal revenue from adding an additional worker, not the marginal revenue per unit.
C. This is the price of the units at this level of sales, not the marginal revenue.
D. The marginal revenue of adding one more worker to a team of 11 equals to the change in the total revenue from 25 units * $49 = $1,225 to 28 units * $47.50 = $1,330. Thus, the marginal revenue is $1,330 - $1,225 = $105. The marginal revenue per unit that was added from adding one more worker is $35 ($105 / (28 - 25) = $35).
