Kelsey is knitting baby items to sell at a craft fair. She has a total of 1,620 yards of yarn to use for the items. A pair of mittens uses 81 yards of yarn and a hat uses 162 yards. She wants to knit a minimum of 12 items for the fair. If the solution region represents the number of pairs of mittens and hats that Kelsey can knit, determine which graph represents the solution set to the system of inequalities representing this situation.