Graph with Q on x axis, P on y axis. Curve S rises from the origin and increases in both x and y dimensions. Line D1 decreases in both x and y dimensions. An arrow points from line D1 to line D2, which is identical in shape to line D1, but shifted one unit to the positive x direction. Dashed lines extend in the positive x direction from P1 and in the positive y direction from Q1, intersecting line S and line D1. Dashed lines extend in the positive x direction from P2 one unit in the positive y direction from P1 and in the positive y direction from Q2 one unit in the positive x direction from Q1, intersecting line S and line D2. Creative Commons

The price (P) of designer jeans is affected by the supply (S) and the demand (D).

Which of these can cause an increase in the price of designer jeans?

Increased demand and no change in supply
Decreased demand and increased supply
Increased supply alone
Decreased demand alone