A seller was able to sell 100 units of good X for a unit price of $5. If the seller now has to offer a dollar discount to be able to sell 100 units of the good, a. the demand curve of good X has shifted to the right. b. the demand curve of good X has shifted to the left. c. there has been a movement up the demand curve of good X. d. there has been a movement down the demand curve of good X