which of the following statements is correct? select one: a. a price floor set at $20 will not be binding. b. a price floor set at $20 will be binding and will result in a surplus of 100 units. c. a price floor set at $20 will be binding and will result in a surplus of 250 units. d. a price floor set at $20 will be binding and will result in a surplus of 50 units.