Ten years ago, a teacher was working at Babies R Us making $12,000 per year. This allowed them to purchase two dress shirts per month from Express. When they received their first job as a teacher, their income more than double and allowed them to increase their budget for Express sweaters to 6 per month. Based on this scenario, the demand curve for Express shirts would a. create an upward slope in the curve indicating an increase in demand. b. create movement along the curve indicating a change in quantity demanded due to the change in price of shirts. c. shift to the right indicating an increase in demand on the part of the teacher d. shift to the left indicating a decrease in demand on the part of the teacher