GRE Sample Test 2 Quantitative Reasoning 2

Plug In values for each set. If P = {1, 2, 3, 4, 5, 6, 7} and Q = {1, 2, 3, 4, 5, 6}, the range of Q is smaller. Eliminate (B) and (C).
If you change P to {1, 2, 3, 4, 5, 7, 6}, and Q to {1, 2, 3, 4, 5, 7}, the range of Q is equal to that of P. Eliminate (A), and select (D).