You should immediately be able to find values of x-y that are larger than -6: 5-4 = 1, 3-2 = 1, etc. To find out if x-y can be smaller than -6, use the smallest number in set x and subtract from it the largest number from set y: -1 - 4 = -5, which is greater than -6, so x-y cannot be smaller than -6 with any combination of x and y. The answer has to be A.