The ratio of dye to pounds of clothing is constant. A worker develops the chart below to show the amount of dye needed for different amounts of clothing.
Clothes Dyeing
Weight of clothing (pounds)
Cups of dye
21 3
42 9
84 12
105 15

For which weight of clothing is the ratio of weight to dye different from the other ratios?
21 pounds
42 pounds
84 pounds
105 pounds