The 20 Residents of the Village of Towneburg Are Considering

The 20 residents of the village of Towneburg are considering hosting a fireworks show next summer.The total cost of the show is estimated to be $1,000 + $10 per unit.Each resident's demand for fireworks is identical: P = 50 - 2 * units as shown below:
The residents of Towneburg would be willing to pay a total of _____ for the twenty-fourth unit of fireworks and the marginal cost of providing the twenty-fourth unit is ______.

A) $20;$200
B) $20;$10
C) $40;$200
D) $40;$10