A graph titled Demand Curve has Quantity Demanded on the x-axis, from 0 to 60 in increments of 10, and Price on the y-axis, from 0 to 20 dollars in increments of 2 dollars and 50 cents. The line has a negative slope.
What principle does this demand curve demonstrate?

quantity demanded increases as prices decrease
quantity demanded increases as prices increase
prices decrease as quantity demanded decreases
prices remain the same as quantity demanded increases